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Chaptef. 



CONTENTS. 



Page. 

I Invention, the Greatest Science in the World i 

II The Foundation of the Science of Invention 2 

III The Primary Power for Driving an Inventor 3 

IV How to Learn What to Invent 3 

V Hindrances to the Progress of Invention 6 

VI Suggestive Ideas 7 

VII The Initial Step 1 5 

VIII Making and Developing Mechanical Inventions 18 

IX Making and Developing Scientific Inventions 27 

X Acoustic Principles as Tools for Making Scientific Inventions. . 34 

XI Principles in Heat and Light as Tools for Making Scientific 

Inventions 38 

XII Principles in Chemistry as Tools for Making Scientific 

Inventions 57 

XIII Principles in Electricity as Tools for Making Scientific 

Inventions 9^ 

XIV "I've got an Idea." 129 

XV Failure and Success I35 

XVI Simultaneous Inventions 13^' 

XVII Simplicity the Result of Specific Invention I39 

XVIII The Age of Invention. — A Cause of Invention I39 

XIX The Government Favorable to Inventors 140 

XX Invention and Capital 142 

XXI Accidental Inventing Exceptional ^43 

XXII Women Inventors I45 

XXIII Problems in Invention I47 

XXIV Conclusion 1^0 



How TO Make Inventions; 



OR, 



mVENTlNS AS A SGIENGE AND AN ART. 



A PRACTICAL GUIDE FOR INVENTORS. 




EDWARD P. THOMPSON, M.E., 

Member American Society of Mechanical Engineers ; Member, an Examiner 
and an ex- Manager American Institute of Electrical Engineers ; 
f"-^ Member New York Electrical Society. 



FIRST EDITION, 



NKW Yo%: OCT 33^1^1' 

D. VAN NOSTR)^ 0Q^tjNGTO^-/j 



23 Murray and 27 Warren"^!! 



TO 

MY ALMA MATER, 

THE 

Stevens Institute of Technology, 

THIS 
BOOK IS dedicated. 



Copyright^ 1891, by Edward P. Thompson. 



4' A 



^A 



Prkkack 



THE style adopted is that of a lecture, and, therefore, it is hoped that the 
use of personal pronouns may be overlooked. 

The object in view is to make a mere beginning in the establishment 
of Inventing as a Science and an Art, but especially to present conclu- 
sions arrived at in the study of inventors and inventions in order that the 
capacity of inventors may be enlarged. If even a single useful invention 
results from the perusal of this book, I shall feel that the time has not been 
spent in vain. 

Not knowing how a book with such a title would be accepted, preliminary 
notices were distributed soliciting subscriptions contingent upon publication. 
I am greatly indebted to those who so kindly sent in such subscriptions, and 
especially to those subscribers who wished me success. The Electrical World 
(New York) I also thank for inserting a series of paid articles on this subject, 
prepared and contributed by me during the year 1884. 

Much encouragement for continuing the development of the subject-matter 
was given by Mr. T. Commerford Martin, editor of The Electrical Engineer 
(New York), and Mr. George H. Guy, editor of Electricity (Chicago), who so 
kindly invited me to deliver a lecture upon this subject before the New York 
Electrical Society in 1890. 

As may be expected, the inventor will in no way be relieved of tedious 
labor by following any instructions contained in this book. I am inclined to 
believe that this will not be the basis of any criticism which may be rendered 
by any opponents or prejudiced minds ; because I have learned and am more 
and more impressed with what I believe to be a fact that a lazy inventor has 
never yet been born. No day laborer makes as many hours a day. The 
physician, missionary, and other philanthropists cannot show a better record 
for diligence of both the body and the mind. In writing this book I have 
borne this in mind, and have felt that there was no danger of making those 
suggestions and giving that instruction which would be rejected by the inventor 
simply because much work was involved. I have recognized, however, that 
humanity does not like things too dry and abstract, and, therefore, I have 
aimed in making the matter as easily understood as possible by means of illus- 
trations and as few as possible of intricate and unusual technical words and 



phrases. It certainly is necessary for an inventor to have knowledge, but not 
to be a great literary scholar. 

The work is particularly exceeding, when it is remembered that an 
inventor, according to Benjamin Franklin, must, in making a great invention 
pass through the three following stages, namely : i. He starts to do that which 
others say is impossible. 2. When he claims to have succeeded, people believe 
him not. 3. When his invention comes into commercial use, hosts of inventors 
appear who claim to have done the same thing before. 

One of the most important elements for ensuring success in any under- 
taking is preparation. At the present time, the World's Fair at Chicago is a 
'* future event," but its success depends more upon what is done before, than 
after the day of opening. Committees are appointed for making preliminary 
arrangements. A site must be chosen first, as to location in the countr)' and 
then as to the particular portion of the chosen city. An engineer is appointed 
for each department of industry. A business department with its managers 
and clerks must be established. The people must be informed and educated 
up to the idea of the benefits and attractions, or the attendance will be small. 
All this is preparation. The drift of this book is similar. It is intended as a 
means of preparation rather than as a collection of mathematical rules to be 
followed in order to make an invention. Napoleon is noted for the display of 
genius in many of his manoeuvres, whereby he conquered nations under 
circumstances which depended upon instantaneously conjured plans developed 
mentally and carried out physically ; but it must be remembered that if he had 
not spent preliminary hours in thought, made scores of maps of the proposed 
attacks, instructed his inferiors as to all the probable and improbable haps and 
mishaps, studied the lives of other successful and unsuccessful soldiers, and the 
histories of other nations, his genius would have counted for so little that there 
would probably have been no exhibition of the same. 

New York. E. P. T. 



CHAPTER I. 
Invention, the Greatest Science in the World. 

Tatham has said : — " Invention is the happiness of man." 
Edison has said that he is happiest while inventing. The Book 
of Truth says : ^' It is more blessed to give than to receive." 
Inventors may say : — ^' We give to the world more than we receive. 
We are happy in inventing. We have often become poor while 
the world has become rich by our inventions. Even when we 
have made our thousands, the world has netted its millions." 

Of all the physical and mental sciences, which is the great- 
est in the world ? Is it Chemistry, Natural Philosophy, Physi- 
ology, Mineralogy, Geology, Electricity, Mental Philosophy or 
Metaphysics ? Most emphatically. No ! The sun furnishes 
light, but of what value is the light if we use it not? The sci- 
ences just named furnish knowledge. Of what value is 
knowledge if it is not used ? Invention is the greatest science, 
if measured by its usefulness to mankind, because it gives to the 
world the practical benefit of the other sciences. It is the sci- 
ence which applies knowledge to useful purposes. Without 
invention. Chemistry and Physics are practically worthless. 
Physics says: — " Heat expands." Invention applies this principle 
and builds a steam engine whose power is due to the expansion 
of water by heat. Chemistry and Mineralogy result in the dis- 
covery of phosphorus and sulphur. Invention makes the match, 
one of the most useful and wonderful and almost magic-like 
inventions ever made. Physics teaches that speaking vibrates 
the air and diaphragms, and that an electric current can be 
rapidly varied from zero to maximum and from maximum to 
zero. Invention vipplies these principles to the electrical trans- 
mission of speech. Geology exhibits the structure of the earth. 
Invention produces thousands of Green's driven wells. 



CHAPTER II. 

The Foundation of the Science of Invention. 

Ever since the time of Bacon, any given science has been 
developed by classifying facts and establishing principles thereon. 
Before the time of Bacon, little progress was made in any sci- 
ence because principles were proclaimed and then facts sought 
to uphold the principles. The new process of Bacon is called 
the inductive system of developing a science ; and the earlier 
process, the deductive system. 

The development of a science by searching for and record- 
ing facts and establishing principles, does in itself assist the 
science to grow ; thus, the science of Physiology, having been 
recorded in publications under classified principles, enables each 
future generation of physicians to acquire easily the principles, 
and to add, from time to time, valuable facts which either 
strengthen old principles or show their fallacy. The science of 
Chemistry forms the knowledge of the chemist, who, knowing it 
in its present condition, can make use of the experience of 
others, and add to its records, because he knows the record of 
the past. So, also, with the more abstract sciences, as those of 
Political Economy, the Sciences of Civilization, Religion and 
Psychology. Before the time of Bacon, any one who desired to 
add to the knowledge of the world worked in the dark. He 
knew little because the knowledge before him was not intel- 
ligently and conveniently collected and classified for his use. 

Philosophical speculations occupied more time, and were 
considered more valuable than experiment. The Royal Society 
in olden times spent several meetings in discussing whether a 
pail of water, with a dead fish in it, weighed more or less 
than a pail of water containing a live fish. Finally, a member 
who was certainly ahead of his age, boldly and unexpectedly 
settled the question by actually weighing the pail of water under 
the two conditions. 

An inventor, who expects the greatest success in conceiving 
and developing an invention, should be acquainted with princi- 
ples of inventing, based upon facts evolved by'the study of 
former inventions ; or else he works in the dark ; trusts to get- 
ting his ideas by accident ; or leaves his inventions in such a 
crude state as to render them practically worthless. The sci- 
ence of Civilization deals with the greatest events of history ; 
drawing therefrom the principles upon which the science is based. 
This book attempts similarly to establish the science of Inven- 
tion upon the history of the greatest inventions and inventors. 



3 

CHAPTER III. 
The Primary Power for Driving an Inventor. 



In becoming a business man, a professor, an electrical engi- 
neer, or engaged in any occupation, the first requisite is to 
have a love for it. If a youth is to be a lawyer, he should first 
determine if he believes he would enjoy that profession. If he 
is to prepare for college, he must first determine if he prefers a 
profession to a business career. Having decided what he likes, 
let him proceed with a concentration of all his energies, and he 
is sure, nine times out of ten, to succeed. The very enjoyment 
of his work, and belief in his own power to succeed, will do 
more for him than any other one element, because all other ele- 
ments are comparatively useless without well-directed and 
honest ambition. 

Love of inventing may be natural or acquired. It grows 
with practice. The more one invents, the more he loves to con- 
tinue. The natural love of cyling or playing games grows until 
it may be said to be acquired. The more one invents, the more 
he loves that employment. 



CHAPTER IV. 
How TO Learn What to Invent. 



Before the introduction of the telegraph system, the quickest 
communication of ideas between two points of considerable 
distance was by post, express or special messenger. Great in- 
convenience was the consequence and often ensued the loss of 
money and non-fulfillment of duties and obligations, in cases of 
death and important business transactions. Everything was 
done by the government and private corporations to provide 
means for lessening the time for transmitting messages. The 
public realized the importance of saving time. Probably thou- 
sands of people realized the inconvenience and injury done by 
slowness of transmission. Every one, substantially, may be said 
to have recognized the inconvenience, the trouble and the dif- 
ficulty. They knew that it would take days and even months 
for their letters to reach certain parts of the world. 
They knew that in the case of death of one of the 



family the funeral would occur before those at a cer- 
tain distance could receive the news. They knew that when 
a great event, such as a battle, was expected to take place in a 
foreign country, ten days or more would elapse before they 
could learn the result. They knew that during a journey of a 
colleague on important business through the country they could 
know his whereabouts and successes and failures with from one 
day to several weeks' delay. In short, they were strongly con- 
vinced of the existing difficulty. They had no doubt as to the 
usefulness of any means which would remove the difficulty. 
Some were resigned as if to a fate. Others hoped and even pre- 
dicted wonderful improvements. But who was it that not only 
realized the difficulty, but had faith that the trouble could be 
removed ? Who was it that not only talked with friends on his 
homeward ocean trip about the inconvenience of slow transmis- 
sion of messages, and not only believed in a remedy, but ex- 
pressed in words that he believed the difficulty could be re- 
moved ? He talked with others more educated than himself in 
order to glean knowledge and make use of it for the public. 
This is a fact, therefore, based upon history, that Morse, the in- 
ventor of the telegraph, recognized the existence of a certain 
need in the world, and not only that, but also believed there 
was room for improvement ; and on top of this knowledge and 
belief he had faith, and followed up his faith by diligence and 
actual work. This fact is apparent also in the study of other 
inventions. It is the public that realizes the existing difficul- 
ties, while it is the inventor who follows up his belief by his 
diligence. Take the case of the invention of the telephone. 
The public appreciated the value of the telegraph for communi- 
cating from one part of a country to another, but to telegraph 
from one part of a city to another amounted to little more than 
sending a special messenger. It was the inventor who not only 
recognized the difficulty, but also undertook a personal task of 
removing it. 

The public realized the danger of boiler explosions. In- 
ventors did also, but they went further and undertook to prove 
that they could remove the difficulty, and as a result invented 
the safety valve and improvements of construction and opera- 
tion, whereby most boiler explosions of the present date — which 
are exceedingly scarce in proportion to the number of boilers — 
arise from sheer carelessness. Public opinion at one time, and 
only lately, denounced electric arc lighting, because it was dan- 
gerous. The cry against high tension currents aroused inventors 
to a belief in means for eliminating the danger, and they have 
already and almost perfectly succeeded, whereby the accidents 



are fewer in actual number, although the circuits have increased 
hundreds of miles. Among smaller, but very important inven- 
tions, may be mentioned the crank-and-gearing combination 
with shutters or blinds. People were aware of the danger of 
catching a cold, letting in flies and mosquitoes, and of other 
difficulties connected with shutting the blinds. The inventor 
also realized the difficulties, but in addition believed that he 
was the one to remedy it, the result being means for operating 
shutters by merely turning a small crank inside of the house. A 
study of the invention of the spring roller for window shades, 
from which fortunes have been made, exhibits the same fact. 
The principle derived may be stated thus : 

Any given individual takes a step toward becoming, or im- 
proving himself as an inventor, who studies the need of the 
public ; learns the difficulties connected with that department of 
art or industry in which the need exists ; excites his mind with 
the belief that he can provide means to remove the difficulties ; 
and proceeds with diligence toward the solution of the problem. 

The truth of this principle is strengthened by its negative 
aspects. Suppose the first step should be not to study the need 
of the public. The consequence would follow in many cases, 
in the production of useless inventions — /. ^., those which ac- 
complish results not wanted. This often does occur. As an 
illustration, parlor skates may be mentioned. An inventor of 
an improved roller skate for to-day is an inventor of that which 
has no market, as skating rinks have gone out of fashion and 
lost their popularity. It is something which the public does not 
want at present, even though it did formerly pay a tribute of 
many thousand dollars to the early inventors and improvers of 
the parlor skate. 

The second element of the principle before stated consists 
in learning the difficulties connected with that department of 
art or industry in which the need exists. 

If there is any one difficulty in connection with any depart- 
ment of art, the would-be inventor may be sure of reward if he 
succeeds in overcoming the difficulty. How is he to become 
aware of the difficulty ? He is to make a business or study to 
this end. If he is engaged with a manufacturer he can daily 
become acquainted with difficulties which prevent the manu- 
facturer from clearing as much profit as he should. At one time 
so much trouble was experienced at sea by the untimely jump- 
ing of the safety valve that steam navigation was well nigh 
abandoned. The engineer of the boiler manufacturer viewed 
the difficulty as something to be overcome, and solved the same 
by substituting a spring for the weight which controlled the 



6 

valve. If he is a student or scholar of science, he can become 
acquainted with difficulties by studying any particular art. If 
he is a business man he can learn difficulties by the habit of 
observation of difficulties met with by himself, In connection 
with his own business, any man can learn some difficulty if he 
will only keep his wits about him and be on the lookout. He 
may meet it in traveling, in business, in his home, in his con- 
versation with others, in the newspapers and in other directions. 
At the present moment exist problems well known to many, but 
yet unsolved, and of all degrees of magnitude, and in all depart- 
ments of every art. Since the learning of difficulties is one of 
the elements of the first principle underlying the science of in- 
vention, it seems but proper that some should be given at least 
for the sake of illustrating what is meant by a " difficulty " for 
an inventor to solve. This matter is treated in the chapter on 
"Problems in Invention." 



CHAPTER V. 
Hindrances to the Progress of Invention. 



Some are desirous of being inventors. They know they have 
a love for it. They admit that there is room for improvement 
and for original invention. They have studied the principles of 
science or of a particular art. They believe that others may 
and will invent. Ask them why they do not invent. The invari- 
able reply is that they believe they possess no genius or inven- 
tive faculty. They imply that some have been born and gifted 
with what they have not. This is not true. Every man has 
more or less power of inventing. Every day every one busily 
occupied uses his power or faculty of inventing when he plans, 
in imagination, his business of the day, or whenever he thinks 
of the best way of carrying out an idea. Let one once believe 
that he does possess the power to invent and it will not be long 
before he will know that the field of invention is shut against 
none. From observation I conclude that the following princi- 
ple is true : A belief of an individual that he himself does not 
possess genius or the power to invent is, in itself, a hindrance to 
the action of that power. 

The corollary which follows is : An individual who will 
admit that he possesses a power of inventing, to a greater or 
less extent, may become an inventor by the proper use of his 



knowledge. Suppose that the inventor of the device for thread- 
ing needles insisted previously upon the assumption that he had 
no genius. He did not so assume. Consequently he received 
an annual income of $ro,ooo from the sales of his patented 
needle-threader, which was at one time so popular a device. 
The inventor of the roller skate cleared nearly $1,000,000, al- 
though during only the last few years of the term of the patent. 
Will any civilized white man assume he has no inventive 
faculty or genius when it is a fact that the Patent Office re- 
cords show that colored men are inventors ? I am personally 
acquainted with a colored man who has not only made electrical 
inventions and received letters patent of the United States, 
but has sold the same. His extreme confidence in his ability to 
invent is easily apparent to those who know him. Some of his 
inventions show a high type of invention ; therefore it seems but 
proper that due honor should be given by mentioning his name. 
I refer to Granville T. Woods, formerly of Cincinati, Ohio. 



CHAPTER VI. 

Suggestive Ideas. 



While I admit the plausibility of an inventor's working ex- 
clusively upon one subject, yet it is often true that he remains 
too long in one line of thought or channel. A certain inventor 
(Catling) failed in protecting a successful screw propeller, after 
working upon that subject for a long time ; but as soon as his 
attention was drawn to another line of work (guns) his enthu- 
siasm revived and he soon made a commercial success. Frank J. 
Sprague stated at a meeting of the American Institute of Elec- 
trical Engineers, that upon his hearing of the great success of 
Brush, Thomson, Edison, and others in electrical inventing, he 
concluded there was room for him also, and therefore made valu- 
able inventions, left the Army, and, as is well known, in a won- 
derfully short time succeeded both scientifically and financially. 
If success does not follow after a reasonable time in any given 
direction, try other departments. 

It has often been stated that the way to invent is to think, 
and keep on thinking. It is almost impossible for one to think 
unless he has whereof to think. He must receive certain im- 
pressions from without before he has anything upon which to 
concentrate his mind. In short, as in all cases where good is to 



8 

be obtained, inventing involves systematic and diligent mental 
and bodily work. The inventor must be given a suggestive idea. 
Probably an invention was never made except by receiving 
some kind of impression from outside of the mind. By study- 
ing past inventions and inventors it is found that certain sug- 
gestive ideas have prompted inventors over and over again, and 
continue to give to the world greater and greater reward. 

The following-headed paragraphs contain some of those 
suggestions which have heretofore prompted inventors: 

A device to do atcto77iatically that which has been done by hand. — 
An early example is that of the eccentric. A boy was obliged 
to turn a valve to let in the steam at each stroke of the piston. 
A later example is an automatic device which, exactly at the 
end of five minutes, in a long distance telephone system, cuts off 
the subscriber's line from use. The operators are apt to give 
subscribers too long. Such inventions are among the most valu- 
able known. They save cost of manual labor, prevent injury 
and accident due to neglect of man, and often do the work 
much better. Progress of invention in this direction can be 
made by taking note of what is at present done by hand, and 
considering if it would not be advantageous to have a device 
which will accomplish the same thing automatically. The work- 
ing out of a device to do it usually requires only ordinary intel- 
ligence. As soon as the boy wanted to go out to play ball and 
not let the steam engine stop, it occupied but a short time to 
rig up a string and lever between the valve and one of the mov- 
ing parts of the engine and make the engine take care of itse.f. 
To make this class of invention, therefore, closely observe what 
is at present done by hand in the different departments of manu- 
facture, electrical installations, commercial traffic, at home, on 
the street, railroad, and everywhere. Again, if three motions of 
the hand are necessary to operate an apparatus, try to make the 
device attend to some of those motions. 

Preve?itmg Loss of Life and Property. — When a serious catas- 
trophe occurs on a railway system, in the street, or anywhere, it 
is the duty, or at least the function, of an inventor to study into 
the cause of the accident and discover, either by personal in- 
spection, by official reports, or by the most reliable means at 
hand, the exact details of operation of the system before, dur- 
ing, and after the accident. An invention which will in prin- 
ciple prevent the same kind of accident in the future is that 
which is likely to become useful when fully developed and ap- 
plied. This has been the manner in which valuable safety de- 
vices and systems have in the past been invented and introduced, 
and therefore it will be a safe rule to follow in the future. 



9 

Since the invention and introduction of the automatic brake 
system of George Westinghouse, Jr., and his associate inventors, 
loss of life and property has been enormously reduced. 
He and they provided means for stopping a train moving 
at a high speed within a distance several times less than 
could be done by hand, and therefore in the case of emergency 
the train could be stopped before an accident was possible. In 
many other ways, accidents have been prevented by this inven- 
tion, which possesses utility in a very high degree. But there is 
a class of accidents impossible to prevent by the automatic 
brake system. Observation of records in the newspaper shows 
that two railway accidents per week occur on an average in the 
United States, with loss of life and property or both. It has been 
proposed through the press that these accidents be made a sub- 
ject of legislation by appointing a committee to study into the 
cause of the accidents ; to learn if there are or maybe means in 
existence for preventing them; to determine if the railway com- 
panies shall be forced to adopt any invention or inventions 
adapted to prevent certain kinds of accidents ; and to consider, 
in general, the best welfare of the public in this connection. In 
a similar manner, other departments of art could be considered 
in regard to means for preventing loss of life and property by 
navigation, chemical manufacture, and electric lighting and 
power. Some inventions in safety devices for railway systems 
are ludicrously interesting, but at the same time plausible. For 
example, there was an exhibition in this city of a system whereby, 
upon two trains approaching each other, the whistles on both 
locomotives are automatically operated so as to notify the en- 
gineers of danger. The whistle of either train is operated 
through electric circuits by the other train, and vice versa, when 
the trains approach within a predetermined distance of each 
other. It is appropriately called " The Tooting System." 

How many hundreds of steam boilers would explode if 
equipped with only steam gauge and water signal, and not with 
a safety valve, which operates in case of danger, whether the en- 
gineer is asleep, intoxicated, careless, or entirely absent. 

Reducing Cost of Manufacture, or of the Cost of the Products 
of Manufacture. — The now well-known wire hat-and-clothes 
hook costs only a small fraction of the former cast iron hook and 
is easier to place. The late embroidering machine does the 
work of dozens of factory girls at less cost and produces supe- 
rior work. The first conception of a telegraph system before 
Morse's new alphabet system was by having a circuit closer on the 
main line for each letter and figure. The cost of a line of 36 
wires from New York would be so great as to discourage capital. 



10 

It never even came into use. The first incandescent lamps were 
half as intricate as an arc lamp. The present machine for setting 
up type by striking keys like a typewriter, although practical, is 
no doubt as intricate in comparison to probable later improve- 
ments, as the first sewing machines were in relation to the 
present forms, which themselves are continually undergoing re- 
duction in cost of manufacture. Aim, therefore, to so modify 
any given device that the same may be manufactured in larger 
quantities for the same money, or so that the products of that 
machine may be produced more rapidly. This is accomplished 
most probably by a radically different construction, whereby 
the cost of the castings for instance may be less ; or whereby 
the number of moving parts, levers, wheels, &c., may be less- 
ened ; or whereby the result is obtained by the application or 
combination of different mechanical principles. Aluminium 
was first obtained chemically, and sold at from $3 to $6 per lb. 
The principle of making its oxide a conductor, by mixing car- 
bon with it, and heating by an electric current, was applied, so 
that now it costs but $1 per lb. Every now and then we learn 
of these wonderful inventions for getting some old results at a 
much less cost. It is one of the most profitable and accessible 
fields for those who are willing to face the problems boldly. 

By "less cost" or ** cheaper" is evidently not meant 
" poorer material " or "careless work." 

J^air Co7npetition. — The fact that one inventor holds a monop- 
oly is not necessarily a reason why a second inventor cannot 
share the profits. There is generally a chance of inventing that 
which will accomplish the same result without infringing the 
patent. Occasionally this is impossible, but oftener it is possi- 
ble. It is better for the community that there should be two 
competing parties. It is probable that both parties will reap 
fortunes. The author does not encourage infrmgement, but fair 
competition among inventors, and therefore greater progress in 
the arts. The inventor who succeeds in " getting around " a 
certain patent, and avoids any doubt of infringement, does only 
right to the community — /. ^., to the majority — and breaks no laws. 
An example is that illustrated by the great monopoly once held 
by the telegraph company. Prof. Bell accomplishes even a bet- 
ter means of rapid transit of messages for moderate distances, 
as measured by the profits to the company ; while the telegraph 
company to all appearances is not at all poor ; neither are their 
numerous detail patents infringed, nor would the original, but 
expired, patents have been infringed had the telephone been 
invented at the beginning of telegraphy. The same general re- 
sult was accomplished by non-infringing means. There are 



11 

many illustrations of this principle ; so that inventors need not 
stop from courtesy to other inventors, from fear of injuring their 
business. The community demands fair competition among in- 
ventors as well as among manufactures and dealers. Proceed, 
therefore, without fear to find out just how broadly a certain 
patented monoply is covered, and exert the utmost power to 
accomplish the same or better results by non-infringing means. 

Slight Circumstances Lead to Invention. — For example, Prof. 
Short, of the Short Electric Railway Co., visited the Electrical 
Exhibition held several years ago at Chicago, and while there, 
became so interested in electric railways by observing a model 
of one, that from that moment he became, and has continued, an 
inventor of electric railway systems and devices. 

Many years ago — /. e., in 1688 — a vessel containing melted 
glass broke, and a portion of the fused mass found its way be- 
neath a large flag-stone, which, when removed, revealed a plate 
of glass. This accident suggested to Thevart the idea of casting 
plate glass. Crandall, who obtained fame through his toy build- 
ing blocks, owned a large glass ball, which seemed possessed 
with life, always rolling where it was not wanted. This was the 
small circumstance which led to nis invention of ''Pigs in 
Clover" by which he cleared over $40,000. 

From the foregoing facts a valuable principle is deduced, 
namely: 

An observation of the ordinary circumstances of the day, 
with a view to invent, assists the desire and attempts to invent, 
and suggests finally the basis of a new and useful invention. 

Experiment a Teacher. — Experimenting for the purpose of 
solving a certain problem often suggests the solution of an inde- 
pendent and unexpected problem. 

Glauber searched long and diligently for the Philosopher's 
Stone, and by putting certain chemicals together for this pur- 
pose found that he obtained a substance radically different from 
either of the constituents. The compound thus produced is the 
medicine which bears his name. It is well to listen thus to the 
dictates of experiment, and not to become the least discouraged. 
Newton tried in every possible way to solve the theory he had 
as to the existence of gravitation. The natural experiment or 
operation of nature in the falling of an apple taught him in a 
manner entirely unexpected. While Edison was experiment- 
ing in telegraphy he saw some operation occur in an experiment 
which taught him a scientific principle he had not before fully 
realized, and at once concluded that if that principle were really 
what it appeared, he would make a talkmg machine. In the 
early days of printing, the type was carved upon wooden blocks; 



12 

but often breaking off, new letters had to be glued on to take 
their place. This taught an inventor, who was seeking for im- 
provement in the art, to make our present movable type. 

Different inventors follow different paths in the process of 
inventing. In some cases they perform experiments mentally 
upon their conceptions. One experiment leads in their mind 
to another, with new suggestions, until finally they are able to 
decide upon the fact of the invention as to whether it is opera- 
tive or not. This is the most economical method. It, in itself, 
trains the mind Lo the power of intense imagination and of in- 
vention. Many preliminary experiments may often be dropped 
by studying books on the subject, to discover just what facts 
and principles exist that bear on the matter in hand. Many 
inventions have been made successful upon completion of the 
first device. A pencil and piece of paper will greatly aid the 
imagination, and will save much useless experimenting. I 
lately visited at his home an inventor of a " Put a Nickel in the 
Slot and Have Your Photograph Taken." The machine did all 
the work. It was automatic from the beginning to the end of 
the process. Although marvelous to behold, and apparantly 
intricate, it was the result of the very first experiment, and it 
did its work not only well, but every time. I found that it took 
but two months for him to reduce the mental invention to the 
physical; but to devise the complete mental invention and to 
experiment with all the movements in the 7nind assisted by 
pencil and paper, occupied the larger portion of a year. 

Some begin to experiment upon the very first conception, 
and even build a full-sized machine at the first, and when the 
difficulties are found another device is built, and so on. This 
method is more expensive and requires more time, and does not 
in itself increase the power of imagination, which is one of the 
greatest aids to an inventor. A harmonious blending of these 
two methods makes the greatest inventor. 

The style followed by the chemist and physicist in their ex- 
perimenting for new principles is often copied by successful in- 
ventors. The former use small and almost minute quantities 
and apparatus, costing very little. Small experiments are as 
positive and often more so than large experiments. Plante ex- 
perimented upon his secondary battery with small quantities of 
chemicals, costing but a few cents each. Distribute your time 
and money on numerous small experiments rather than upon 
a few large ones. 

Reparation. — It is well known that tons of zinc have been 
wasted by the telegraph companies by throwing away the stubs 
of crow-foot zincs used in batteries. Georges d'lnfreville has 



13 

made an invention whereby this waste need not exist. Other 
important inventions could be quoted to illustrate the same 
teaching, namely : — When a part of a machine wears out, and 
must be thrown away, let the knowledge thereof be an incen- 
tive to prompt to a modified construction whereby the worn-out 
part may be replaceable by a new part, so that time and 
material shall not be wasted. In some old instances, a whole 
valuable device was thrown away until inventions were made 
whereby it was only necessary to throw away that part which 
was worn out. 

Critical Inspection of Crude Devices. — Scarcely does an in- 
ventor see the invention of another but that it looks very crude, 
and that he makes valuable improvements, whereby both make 
more profit than either could have hoped to have made 
alone. The one has had practice perhaps in conceiving prolific 
ideas, but lacks practice in making mechanical inventions. He 
puts the crude device upon the market. It is about to fail. 
The second inventor, equipped with the broad ideas, applies his 
practice obtained in making mechanical inventions and im- 
proves so greatly upon the crude device as to reap benefit in 
conjunction with the first inventor. 

A Device for doing by Elect?'icity that which had previously 
been done by some other Agency. — Since the time of Cain and 
Abel welding has been accomplished by hammering. Only in 
modern times has a successful device been constructed whereby 
not only can ordinary welding be accomplished by the electric 
current, but the device will weld that which cannot be welded 
by the old process. Inventing is often like a horse-race. All 
the jockeys are endeavoring to reach the same goal first, and 
there is a theoretical possibility that all will get there at the 
same fraction of a second, but this scarcely ever happens. 
Possibly two arrive instantaneously apparently. In any event, 
the one who beats is the one who receives the prize. For the last 
decade inventors have been attempting to apply electric cur- 
rents to welding. The one who first applied the electric con- 
verter principle where the maximum heating current is obtained 
from an electrical source was the first to succeed, but soon 
afterwards others made the same invention independently. 
Other results are being sought through the electric current, and 
inventors should be awake to this suggestive idea and attempt 
thereby to widen the usefulness of electricity. 

The successful application of welding by electricity is some- 
what similar to the introduction of the air brake. Others had 
attempted the solution of the problem, but fell short of success. 
Judges Walker and Swayne set forth in an important case (2 



14 

Bann and Ard., 55, 1875), that, although others had conceived 
the idea of air brakes before Westhinghouse, yet he is the first 
legal inventor and entitled to protection because the first to in- 
vent a practically operative air brake, which is so important to 
the safety of human life and property. An important principle 
is contained in the above illustrations. It is often more important 
to be the first to conceive broad ideas than to be first to 
produce the best. 

Omission. — By omitting one or more of the elements which 
were at first thought to be necessary, but which one finds may 
be omitted and the same or even better results obtained by a 
new mode of operation, an invention is made. If by omitting an 
element the device is worse than before, then there is no inven- 
tion. A certain party omitted the board foundation of a 
Nicholson pavement, but Judge Blodgett decided that these 
omissions constituted no invention ; but a reconstruction of a 
machine so that a less number of parts will perform all the 
functions of the greater is the invention of a high order. In 
a friction clutch for hoisting-machines the patentee dispensed 
with one of the friction cones and flanges found in the prior 
art, re-arranged the machine accordingly and put a s]:)ring where 
it was needed, and the patent was upheld by Judge Wheeler. 

Transposition. — An inventor may often improve the manufac- 
ture by changing the relative positions of the parts of a device if 
at the same time he accomplishes the same or better results. 
Permutation locks have thus been improved; also watchman's 
time recorders. An inventor made a new location of a hinge 
and spring catch in a lantern and remedied a great difficulty in 
manufacture and use, and its advantages were immediately 
recognized and other manufacturers began to copy. The patent 
was upheld by Judge Wallace. 

Change of Form. — Construct one or more of the parts of 
such a form or sha])e that an otherwise essential feature may be 
omitted. One by the name of Russell modified a water pump 
by constructing the inwardly projecting flange of such a form 
that it could be used wholly for the base of the pump, and thus 
do away with any frame-work. His patent for this improvement 
was upheld by Judge Colt. 

By a mere change of form a new result is often obtainable. 
A patented baby-jumper differed from other jumpers in a back- 
ward curvature of the suspension rod to prevent contact with 
the child, and this improvement in mere form was held patent- 
able by Judge Blodgett. The manufacture was as cheap as with- 
out the curvature, but as the result was improved with the 
change of form, more was obtained for the same money. 



15 

A similar case is that of a carbon filament for incandescent 
lamps being made with a curve like a horseshoe, instead of 
straight. They are equally cheap to make and they possess the 
improved result or advantage of having the leading-in wires 
enter the same end of the lamp bulb, and of exposmg more 
illuminating surface per volume of vacuum space. 

Combined Inventions. — An inventor may often obtain inven- 
tion by combining the merits of two or more devices into one. If 
the result is an invention of equal convenience, cheaper than 
both elements and as meritorious as both, the single invention 
is a true invention according to Judge Lowell. 

As an illustration, the preserving of meat may be taken. 
Enveloping meat in a covering of fibrous or woven material is 
old. Subjecting the meat to the action of a current of air of 
suitably low or regulated temperature is also old. Combining 
the two elements is pronounced new and patentable by Judge 
Nixon. 



CHAPTER VII. 
The Initial Step. 



It is not enough to have a love for inventing. You may ad- 
mire other inventors and inventions, and may think how satis- 
fied and prosperous you might be if you could make a success, 
and you may even realize some problems which need solving, 
and yet not be an inventor. More is needed than mere desire. 
In order to get there, one step must be taken at a time. What, 
therefore, is the first step ? 

An inventor deals with positive results and absolute condi- 
tions, and not with chaos and creation. He proceeds in a man- 
ner peculiar to itself, and not in a common way with other 
workers. Mathematicians, physicists, chemists, carry out con- 
ditions, and obtain a result ; and the fulfilment of the same con- 
ditions always produces the same result; 2X3X4 always equals 
24. There is positively no exception. The physicist follows 
the same law. If he wishes to transfer electricity from one 
point to another he must fulfil the proper conditions. An elec- 
tric current of about two volts always decomposes water into 
hydrogen and oxygen gases. The result is sure to come, and 
there is but the same result. 

With the inventor everything is just the opposite. His 
given quantity is the result, while the unknown quantities are 



10 

the conditions. In the above arithmetical problem his known 
quantity corresponds to 24, and it is to find the conditions 
which, when obeyed, will give 24. It is evident that the result 
might be obtained in many independent ways ; thus 
2X3X4 equals 24 

6X3+1+5" 24 
30—6 " 24 
(2X6)+ (6X2) " 24 
and so on indefinitely, and limited only by the capacity and 
patience of the mathematican. Does it not follow, therefore, that 
an invention has different answers, and that a problem in arith- 
metic has only one answer ? Yes ! this is the general rule. The 
product 24 may be obtained by carrying out many conditions, 
or by few. i + i + i + i, etc., will eventually result in 24 as the 
answer, or simply 2 X 12 = 24. The inventor should aim for the 
fewest conditions. The result should be obtained by as few 
steps as possible. 

Analysis. — The result sought is usually compound, not ele- 
mental. There is scarcely an exception to this, although before 
the trouble is taken to analyze it the result seems elemental 
and not compound. The first essential step consists in analyz- 
ing the problem into two elements and if possible into more 
than two. Each element may itself be a compound. This analy- 
sis is exceedingly important, and will aid in systematic work. 
Nothing is more important in inventing than to have a target. 
He who has a definite aim is the one who conquers. 

To illustrate the point, let an example be taken — e. g., the type- 
writer — $20 on every Remington typewriter sold are said to go to 
the inventor. The claims cover only the particular construction of 
the machine, the elementary ideas being public property. Sup- 
pose it is desired to invent a radically different typewriter from 
the Remington or any other form found in practice. The initial 
step is to analyze the problem. 

The following example will serve to illustrate how a result 
is divisible into its elements: 

I. T/ie general result is a machine which will write or 
print words and sentences when properly controlled by an 
operator. 

The elementary results are (a) means for making the type to 
strike the paper at proper intervals of space ; (b) means for 
moving the paper through the proper space after each letter is 
printed; (c) means for being able to see the printing during 
the operation, as in handwriting; (d) means for retracting the pa- 
per when a mistake is made ; (e) means for making, simultaneously, 
multiple copies of the printed matter; (f) means for moving the 



IT 

paper at the end of each line; (g) means for giving a signal 
near the end of each line; (h) means for easily replacing a 
filled sheet by a new sheet; (i) means for adjusting the machine 
to print the lines at any a-pproximately desired distance apart; 
(j) means for beginning the lines at a given margin; and (k) 
means for printing both capitals and small letters, figures, and 
punctuation marks, and possibly for printing French, German, 
or some other language besides English. By this analysis 
a complex problem is divided into eleven independent 
simple problems, which upon further consideration may be 
found divisible. The power of analyzing results comes by 
practice. Sometimes the inventor needs to obtain a new result — 
/. ^., doing something which no one ever thought of doing. 
Here, also, the first step is analysis. One who wishes to train 
to be an inventor or to improve his qualifications will find 
it profitable, just for the practice alone, to take a new or old re- 
sult and try to divide it up into as many sub-results as 
possible. 

The practice in analyzing should be: 

1. Gradual. — Do not begin with intricate problems. What 
would be thought of an architect who tries to design a palace 
before he can design a cottage ? Begin on the simplest 
problem and then pass to the greater and more complex prob- 
lems. , 

2. Continuous. — Some men are very enthusiastic at intervals 
in any given undertaking and at alternate intervals lose their in- 
terest. They are early and late at work upon their scheme, and 
just as they are thoroughly saturated with the subject and prob- 
ably near success they allow their mind to be transferred to 
some other subject, forgetting the former until it is too late. 
Recreation is good and should be practiced, but a loss of 
enthusiasm should not be allowed. Continually maintain the 
spirit of intense thought, stopping only for recreation and other 
matters of business, taking up the practice again with renewed 
enthusiasm. 

3. Special. — The inventor should confine himself, not to a 
special device, but to that department of invention in which is 
to be employed his special knowledge and experience. Thus 
a mechanic can do better in analyzing problems bearing upon 
the particular mechanical device for carrying out a broad 
scientific invention than in conceiving a plan for multiplex tele- 
phony. When he understands the principles of the multiplex 
telephony he can then analyze the problem of obtaining the 
same results by less movements, or fewer parts, or in a radically 
different manner, leaving the system comparatively worthless 



18 

without the use of his improvements. On the other hand, 
scholars and professors, having a broad knowledge of all things, 
do not need to practice analysis on mechanical problems, but 
those relating to methods, chemicals, systems, and to the ac- 
complishing of new results. The ordinary manufacturer, 
partly learned and partly a mechanic and partly a business man, 
may practice by analyzing medium problems, getting additional 
assistance from the mechanic, the professor, or books. 

Varied. — There is a sense, though, where practice should be 
varied. One is apt to dwell upon improvements of the devices he 
daily meets with. This makes for him a very narrow field. He 
does not get a sufficiently varied practice. He should endeavor 
to broaden his knowledge through books and other sources of 
knowledge. A man occupied in business is apt to make inventions 
relating to stationery, ink bottles, blotting pads, fountain pens, 
&c., whereas his evenings and spare time could be occupied with 
the exhaustive study of some particular and newer department of 
science or industry than that which occupied the attention of 
the scribes in the year i. Let the problem, therefore, relate to 
something special, but do not narrow it to the small number of 
devices you are apt to meet day after day and year after year in 
your routine of employment. 



CHAPTER VIII. 
Making and Developing Mechanical Inventions. 



From a study of inventions I establish the proverb that a 
problem known is a problem half solved. The only exception 
is the case where natural laws prevent. An old problem, mean- 
ing the same thing by opposites, is that a double-minded man is 
unstable in all his ways. The problem must be /^;2^w-^. It must not 
be simply a vision, an indefinite difficulty to be overcome, but it 
must be analyzed. The next step — the conception — is the mental 
doing of something in order to get one of the elemental results; 
and then doing something else to get the second elemental re- 
sult ; and so on, until each elemental result is accomplished in 
the mind. This will be found to be the easiest part of inventing. 
The invention will be very crude at first. It will be very im- 
practicable, and perhaps so intricate and complex as to lead to 
discouragement. Do not expect to get at once the best way 
of obtaining the result. This has never been the rule with other 



19 

inventors. The first form of mental device is crude. Out of 
ten men having sufficient knowledge, and working for the same 
solvable result, there will scarcely be one but will devise so77te 
mental invention for obtaining the result. In order to arrive 
quickest at the simplest solution one should travel by guide- 
boards, which themselves will not serve as horses to carry him 
to his destination and thereby relieve him of the tedious walk 
and work, but they will be so useful that if they were not there 
he would have to guess the way. What are the guides which 
will serve to make the simplest conception come the quickest ? 
They are given in the case below regarding the arc lamp. 

The developing process depends upon the class to which the 
proposed invention belongs. All inventions, fortunately, are 
found to be divisible into two classes, for purposes of develop- 
ment — Mechanical and Scientific, and each of these into — 

Kinetic and Static. — Samples of the former are theprinting 
press, typewriter, cotton-gin, phonograph, annunciator, harvest- 
ing machine, and spinning jenny ; and of the latter are cars, 
buildings, aqueducts, steam boilers, certain tools, etc. 

The distinction is this: Kinetic — meaning, literally, relating 
to motion — describes all those inventions in which the elemental 
results or steps of the problem are carried out by elemental 
motions, and the whole problem by a combination of motions. 
Static — meaning the reverse of motory — is a term which in- 
cludes all those inventions in which the results are accomplished 
by a combination of stationary elements, varying in form and 
number, and bearing certain fixed relations to each other. It 
includes all devices and products in which motion is not one of 
the essential elements. 

Kinetic Inventions. — Comprehension in the abstract is diffi- 
cult; therefore let an example be considered. Among the best is 
the arc lamp. Let it be supposed that the arc lamp is capable of 
simplification, that it has not yet reached its simplest form. The 
initial step, as by the preceding chapter, is to analyze the result. 

General Result. — The general result is to produce a combina- 
tion of motions which will result in the production of an elec- 
tric spark of constant length. Every problem in kinetic in- 
vention is to produce a combination of motions in order to ob- 
tain the final result. Knowledge, obtained by the experience of 
others, furnishes us with the fundamental and necessary infor- 
mation, that the heat of the arc burns the carbons away, so that 
the spark tends to grow longer. 

First Elemental Result. — The first motion of the carbon or 
carbons, in order that the spark may exist, is that they should 
either be brought together and moved away ; or, if already in 



20 

contact normally, to be moved away from each other to such a 
distance as to produce the predetermined length of arc. Decide 
upon the simpler of the two. Let it be supposed that they are 
in contact normally. The first result to be obtained, therefore, 
is to produce such a motion that the distance between the car- 
bons may quickly increase from zero to maximum, and remain 
at maximum or a little under maximum. The following ques- 
tions present themselves: Shall the motion be rectilinear, curvi- 
linear, vibratory, circular, or elliptical or a combination of two 
or more of the above ? In the present problem this question 
is to be answered by the inventor. 

First Elemental Invention. — Enumerate in the mind, or on 
paper, all the different ways in which the distance between two 
masses may be increased. It is true too often that the first device 
is crude because the inventor did not stop to consider several ways, 
and choose the best. The different sources of power are fur- 
nished by knowledge, and are to be enumerated in each ele- 
mental invention. These primary forces, with their modifica- 
tions, are heat, light, magnetism, electricity, gravitation, chem- 
ical action, contraction, weights, wound-up springs, 
explosions, tides, waves, wind, earth's magnetism and currents, 
cohesion, adhesion, pressure, primary and secondary batteries, 
thermopiles, electric, steam, vapor, gas and other motors, and 
combinations of two or more of the above. In every elemental 
invention these sources of power should be considered and the 
best, single or combined, chosen. The means for communi- 
cating, or changing the direction, or varying the source of 
power, should also be chosen from an enumerated list. To- 
gether with their modifications, they are, in part, the lever, 
screw, wedge or inclined plane, pulley or wheel, smooth or 
toothed, belt, magnet and armature, compound lever, pawl 
and ratchet, crank, mediums, such as gas and liquid, cam, 
tackle, wheel and axle, worm gearing, bevel gearing, escape- 
ment, frictional gearing, idle-wheel gearing, pendulum, 
toggle joint, and parallel-motion device. The first elemental 
invention consists in combining one or more of the above 
sources of power with one or more of the above means for 
communicating and directing the power, until that combination 
is obtained wliich is the best in the opinion of the inventor. 
To be sure, this is a tedious and lengthy o])eration, but there is 
no short road for the inventor. He must follow the guides and 
be willing to plod his way. If there are ten means of com- 
municating power the number of possible combinations is in 
the thousands. How improbable, therefore, is it for one to 
" hit " upon a thing ? It is possible, but not probable. 



21 

Second Eletnental Result. — If the lamp is for ordinary use, 
one carbon may remain stationary and the other fed. If for a 
focus lamp in locomotives or magic lanterns, both carbons 
should be fed. The questions which should be asked, as in 
similar kinetic inventions, are: Shall the carbons move simul- 
taneously or alternately; in a linear or curvilinear direction; 
with uniform rates, continuously, or intermittently, or vibratingly; 
fast or slowly; by independent sources of power or jointly by 
the same power, or with a combination of two or more of those 
motions? 

Second Elemental Invention. — In order to give both carbons 
the proper motion the same steps in combination should be fol- 
lowed as in the first elemental invention, remembering the fact 
that one of the carbons is consumed about twice as fast as 
the other. 

Third Elemental Result. — The mechanism obtained by the 
former step is useless without means of regulation. In numer- 
ous devices in other departments of industry regulating 
mechanisms are required. The same principle of invention 
which applies to the one applies to the other. What is the 
exact meaning of regulation as being a result? What object 
must be accomplished? The mechanism obtained by the 
second elemental invention does not act uniformly with the con- 
sumption of the carbons. If the carbons burn away so fast 
that the arc distance increases, the mechanism should hasten 
the speed of the carbons, and vice versa. 

Third Elemental Invention. — What force shall be used to 
regulate? The force which causes the irregularity. This is 
found to be true in other regulators. In the steam engine the 
load or power v/ith which the mechanism moves is the regu- 
lating power for operating the governor. This is equivalent to 
saying that the steam pressure is the force which regulates the 
flow of the steam through the throttle. In the dynamo regu- 
lator the increase and decrease of current are the regulating 
power, and so in arc lamps, the regulating power is the variation 
of the current by the medium of a magnet. This rule is gen- 
eral, not absolute; therefore it is necessary to consider if the 
regulation can be effected by other sources of power. Having 
decided what source to employ, the point of application of the 
power should be considered. As many points as possible 
should be reviewed. In a clock it is sometimes applied to an 
escapement, while in an electric-clock system it is applied to a 
central clock once a minute or once an hour, and thereby all 
the clocks are regulated. In the same manner much tedious 
labor must be exercised in enumerating the various regulators 



22 

in other departments of industry in order to suggest to the mind 
the possible and preferable point of application of the power. 

The Last Elemental JRcsi/lt aiid Invention. — Before combining 
elemental inventions to form the general one sought, some new 
and additional result should be considered, whether this is a 
problem of the arc lamp or not. At a certain stage of the arc 
lamp industry it was necessary to switch off the lamp, and 
throw in the main line by a hand switch, and therefore the 
automatic cut-out was invented, which, however, is now expired 
as to the patent. In inventing there should be considered any 
additional results over the usual results. They may consist in 
certain attachments or in that portion of the invention relating 
to static invention. 

Consideration of other devices in a similar manner will up- 
hold the principle of invention that kinetic mechanical inventing 
consists in combining those elementary or compound motions 
which are adapted to produce the results sought. This is the 
secret, and it involves and necessitates preliminary practice and 
preparation before the inventor can expect to solve any very in- 
tricate problem. 

Motions. — It is fortunate that the inventor is not obliged to 
discover motions. These are very old, although every inventor 
may not know them or cannot call them to mind at will. No 
new elementary motion has been discovered for many years ; 
but the inventor has combined and re-combined them with such 
wonderful results as to make all the classes of machinery at 
present known. The number of combinations of the present 
known motions is in the thousands. 

The inventor must know the known motions before he can 
expect to make any headway; further, he should know them by 
heart, and should experiment in their combination for the solu- 
tion of problems, whether important or not, and he should 
analyze important kinetic mechanical inventions. The more 
important elementary and compound motions are given and ex- 
plained below. 

In the first place, all motion is relative — not absolute — be- 
cause no absolutely stationary particle exists as far as known. 
All things on the earth move because the earth itself moves. Also, 
the molecules of a body are always in vibratory motion. For 
the purposes of the inventor, the earth may be assumed to be 
fixed, and that motion is to be considered relatively to the 
assumed stationary earth, or to movable or fixed points or 
objects upon the earth. 

The shortest distance between two points is a straight line. 
A particle may move in that line, and in so doing has rectilinear 



23 

motion, the simplest motion known, and, in short, the only 
elementary motion known. Another very simple motion 
is curvilinear motion, but when resolved is found to consist 
of two rectilinear motions occurring or at least tending to occur 
simultaneously at the same time. This principle of motion is 
beautifully illustrated by the writing telegraph, using two inde- 
pendent currents. The motion of the hand to make a hori- 
zontal rectilinear line gradually increases the strength of a 
distant magnet by means of a delicate rheostat. The motion of 
the hand to make a rectilinear line perpendicular to the first 
increases the strength of a second distant magnet near the first 
and perpendicular to the same. Each magnet's armature is 
pivoted to and moves a common pencil. Whatever the motion 
of the hand (rectilinear or curvilinear), the magnets cause the 
pencil to have the same motion, and yet the armature of each 
magnet can move in a rectilinear line only. The pencil par- 
takes of the combined motion of the two armatures whenever a 
slanting or curved line is formed. If the hand moves in an 
ellipse, the pencil, moved by the magnets, moves in an ellipse, 
and so on for every motion. The pencil sometimes has rectili- 
near and sometimes curvilinear, but the armatures always have 
rectilinear motion. A curved motion is therefore a combination 
of rectilinear motions. 

The simplest form of curvilinear motion occurs when a body 
has circular motion. The body, while in motion, remains equally 
distant from a fixed point. Parabolic motion is that in which 
the body moves simultaneously in two directions at right angles 
to each other, with velocities which are respectively accelerating 
and constant, the accelerating increasing as the square of the 
distance. Other forms of curvilinear motion are elliptical, 
sinusoidal, being in that curve assumed by a flexible cord sus- 
pended loosely and having its ends attached to two fixed hori- 
zontally located points ; spiral, being in a curve, having the 
appearance of a snake coiled upon the ground or like the spring 
in a watch; helical, being in a curve represented by the ordinary 
helical spring; hyperbolical, to the eye apparently like the para- 
bolical, the curve of the hyperbola being obtainable by the 
intersection of a conical surface by a plane parallel to the axis 
of the cone; epicycloidal, being the motion of any given particle 
in the circumference of a wheel when that wheel rolls either 
upon the outer or inner side of a circular line; cycloidal, being 
in that curve formed by a point in the circumference of a wheel 
rolling upon a straight line and remaining in a given plane; 
curtate-cycloidal, similar to above, except that the moving point 
is upon a projection extending externally to the circumference ; 



24 

and prolate-cycloidal, being the same as in the above case, ex- 
cept that the moving point is attached to the wheel within its 
circumference. 

Curved or rectilinear motions are divisible into intermittent, 
continuous, accelerating, diminishing, alternately accelerating 
and diminishing, rapid, slow, gradually accelerating or diminish- 
ing, reciprocating, /. ^., first in one direction and then in the 
other, and abruptly accelerating or diminishing, and periodical, 
being that motion in which the object moves for a while and 
then stops for a while, and then moves, &c., differing from in- 
termittent motion in that the periods of motion are definitely 
durable and not apparently instantaneous. Parallel motion is 
that in which a point moves in a straight line parallel to a given 
straight line. Sun and planet motion is that in which one wheel 
rolls upon another which rotates upon a fixed axis. 

Something should be said in regard to the nature of the com- 
bination of the motions for producing an invention. Is it like a 
chemical combination where the compound is different from any 
of its constitutents, or is it like a mixture where the elements of 
the mixture retain their individual properties ? It is sometimes 
analogous to the compound and sometimes to the mixture. The 
curvilinear motion is similar to the compound, because the recti- 
linear motions in the curved line are infinitesimally small, and 
can practically be said not to exist. Practically the curvilinear 
motion is that in which its constitutents lose their indentity un- 
til analyzed, as in the case of a chemical compound. In the steam 
engine such a compound motion is found where the crank-pin 
moves with a circular motion. This circular motion is combined 
with the motion of the other parts of the engine, not as in a 
compound, but as in a mixture. Thus the eccentric, governor 
and slide valve have motions which taken together are essential 
parts of the invention, and yet they are as distinct as if each 
were a distinct device. The word " combined " therefore is a 
general word in the science of inventing, indicating either an 
intimate union or a mere mixture of motions. 

Afialysis of the Motio7is of Kinetic Mechanical Inventions. — 
Another analogy exists between invention and chemistry. The 
student in both cases becomes better prepared to solve problems 
of a certain class by analyzing existing combinations. By un- 
derstanding the analyzing of chemical compounds of a certain 
class he is better prepared to obtain a new compound by com- 
bining chemicals ; so also, by becoming expert in the analysis of 
an invention in the class of kinetic mechanical inventions, he is 
better able to solve a given problem in this class by combining 
the proper motions. A few examples are given, not only for 



25 

such practice, but to illustrate the above-stated principles of 
inventing. 

Sewing Machine. — One part of the thread must pass through 
the cloth in one direction, and a contiguous portion of the 
thread must return through the cloth in an opposite direction. 
The motion which is given therefore to the thread is reciprocat- 
ing if it is desired to imitate sewing by hand. If the machine 
is to be operated by the foot, another motion — that of the 
treadle — is also reciprocating. After the thread is passed 
through the cloth some motion is necessary in order to prevent 
some of that portion which has passed through from returning, 
or else no stitch will be formed. This motion is different in 
different machines, and this feature admits of fertility of combi- 
nations. In general, the motion is such as to tie a knot in the 
thread, which serves the same purpose as a rivet head in the 
manufacture of sheet-iron articles. When the thread comes 
through sufficiently far a loop is formed. In one type of 
machine two peculiarly shaped prongs, somewhat like the fans 
of an electric motor, are mounted upon a rotating shaft, except 
that they are pointed. The prongs enter the loops and release 
them at such relative times as to be ready to form knots which 
are so artistic in appearance as to be used often for embroider- 
ing. It should be said that this rotary motion is coupled with a 
reciprocating finger, which acts at right angles to the motion of 
the prongs, and reciprocates at such relative times as to assist 
the prongs in forming the knots. It is well known that sailors 
can tie many different knots, and similarly the motions and 
relative motions for tying the knots in the thread may continue 
to change until all the kinds of knots are exhausted, and the 
motions may vary in different machines for producing the same 
knot. In another type of machine two threads are employed, 
and the motions are such as to intertwist or intertie the two. 
Another important motion is necessary in a sewing machine. It 
is a periodical motion of the cloth, which is moved the length of 
a; stitch and which is held fixed for an instant at every stitch. 
This motion could be made by the hands of the sewer, but the 
motion would be defective ; it should be automatic. Another 
motion is also periodical, being that which feeds the thread to 
the needle combined with a friction device for holding the 
thread at any desired tension. These motions are all derived from 
the reciprocating motion of the foot. This reciprocating motion is 
converted into rotary motion of a shaft, which corresponds there- 
fore to the shaft of a machine shop, by means of which different 
machines, as the lathe, planing machine, drill, gear cutter, &c., 
may be operated. In the sewing machine each one of the 



20 

motions desired is likewise obtained by mechanical connection 
with this shaft. 

Clock. — The day is divided into 24 hours, each hour into 60 
minutes, and each minute into 60 seconds. One hand indicates 
the hours; one the minutes, and one the seconds. The three 
hands have rotary motions, with different but uniform motions, 
sometimes about different axes and sometimes about the same. 
In some the source of motion is circular, as in the wound-up 
main-spring, and sometimes rectilinear, as in the wound-up 
weight. Again the primary motion may be reciprocating as in 
the case of a magnet and its armature. In all cases, the primary 
motion is generally immediately turned into rotary motion of a 
shaft or arbor from which the other motions are derived. This 
motion is true in a large class of kinetic mechanical inventions; 
the primary motion is first converted into a continuous rotary 
motion of a shaft. The motions of each hand of the clock must 
be so uniform as not to vary a second if possible during a year; 
but of course this is impossible. The primary motion is 
generally a very powerful motion and tends to feed itself out 
in a few seconds. Therefore it must be checked, and allowed 
to feed out intermittently; a little each instant, as is generally 
done by an escapement or balance wheel. The expansions and 
contractions of the pendulum by heat are periodical motions, 
which cause variations of velocity of the hands, whereby the 
wrong time would be indicated, except by automatic motions of 
contrary direction, which will neutralize those of expansion and 
contraction. The pendulum is maintained of the same actual 
length between the point of suspension and the center of the 
pendulum by such an arrangement that the expansions of certain 
parts of the pendulum cause them to shorten, while expansions 
of other parts cause them to lengthen, whereby the average is a 
non-variation of its length. Contractions by cold similarly have 
no actual effect upon its length. Since the hands must have 
different relative velocities, the wheels which gear with one 
another must be of proportionally different diameters, the rule 
being that when two circles of different diameters are geared 
together the smaller will make complete turns as much oftener 
as it is smaller in diameter. 

Adding Machine. — In this, the figures o, i, 2, 3, 4, 5, 6, 7, 8, 
9 are moved to distances proportional to the distances repre- 
sented by the numbers themselves. A series of wheels will 
accordingly, by proper gearing or lever connections, move 
corresponding distances. In order that these wheels may not 
move back again with the figures (which must return to their 
original positions to be ready for a second, third, &c., move- 



■ 27 

ment), the ordinary pawl and ratchet are usually employed. 
The sum of the distances moved through by index hands on 
the wheels will be equal to the sum of the particular figures 
which were moved in the first place. 



CHAPTER IX. 
Making and Developing Scientific Inventions. 



The following principle of the science of invention holds 
true in reference to a large class of past scientific inventions, and 
it may, therefore, be assumed to hold true for many future scien- 
tific inventions. It is formulated thus : — 

An invention may be made by applying one or combining two 
or more principles of physical, electrical, or chemical sciences 
to a new and useful purpose. The corollary to this is : Any 
given problem of invention may be solved by becoming 
acquainted with the principles of physics, electricity, and chem- 
istry, and then searching for principles which by their combina- 
tion will produce the result sought. 

Both of these principles prove the preference and almost the 
necessity of thorough scientific education on the part of the in- 
ventor. I believe it would be for the good of the industrial arts 
and the public to establish in our various scientific colleges 
a class for the development of the power of inventing. At pres- 
ent, students study science and store it away in their brains, as 
though the storage were to be permanent. By the time they 
undertake to use the knowledge they have forgotten most of it. 

An exercise is needed whereby the student will be encouraged 
and assisted in making use of the scientific principles he 
learns. Let the professor of this department give the student a 
principle for application to some useful purpose. If the in- 
vention proves to be old the exercise is no less valuable. It 
will be original, even if not novel, and will thus serve to train 
the inventive faculty and assist in forever fixing the principle in 
the mind. 

Suppose, for instance, that he should be asked to make prac- 
tical use of the electrical principle, that the substance selenium 
is a conductor of electricity when exposed to light and a non- 
conductor when in the dark. 

We can imagine one student proposing to solve the problem 
of rising with the sun. He would have an electric bell in cir- 



28 

cuit with an electric battery and with a piece of selenium, 
which would hang in the window. No current would pass in 
the night because the selenium is in the dark, but it would pass 
and ring the bell when exposed to the light of the rising sun. 
Another student would probably suggest the wonderful in- 
vention of the photophone, in which is employed this principle 
for transmitting sound. Another student might propose to make 
a meter for measuring the amount of energy consumed by an in- 
candescent lamp during each month, by causing the selenium to 
be near the lamp. While the lamp was in, a local and small 
current would flow and operate the clock-work; when the lamp 
was out, the clock-work would stop. My readers may per- 
haps think of as many different applications of the principle 
as there are individuals, and some may result in a val- 
uable and novel invention; but let me ask how many such ap- 
plications of principles and facts can be made by a would-be 
inventor if he does not know the principles ? Where can he 
find these principles ? In books and periodicals on science; in 
miscellaneous readings and in the course of experiments. He can 
obtain them also by conversation with his acquaintances, 
and especially from those who have made a systematic study of 
science. 

In order to make use of the principle of invention, set forth 
in the last corollary, the inventor should first decide what 
problem he wishes to solve and then search books ; search 
his mind for any hidden principle he may have learned a long 
time since; converse with scientists if possible, and do every- 
thing which will acquaint him with the principles, and as each 
one appears think upon all of its bearings, to discover if it is 
possible to combine it with another principle in the solution of 
the problem. Suppose the problem is to transmit speech elec- 
trically — /. (?., the same problem that was solved by the first in- 
ventor of the telephone. We can imagine him seeking here 
and there for the principles and facts in the science of sound, 
electricity, and motion. He considers the same individually 
and collectively. 

Or suppose we consider a problem which has not yet been 
commercially solved, the conversion of an alternating current 
into mechanical power; or, more briefly stated, the invention of 
a commercial alternating current motor, printing telegraph, 
electric meter, &c. In the same manner that other great in- 
ventions have been made and in accordance with the above 
stated corollary, the inventor must review the simple and com- 
plex principles and facts of science and mechanics with the ob- 
ject of applying the same to the solution of the problem, if the 



29 

problem is capable of solution ; that inventor who does this 
work most thoroughly and quickly will be the most successful. 

One of the greatest difficulties in making this class of in- 
vention is that of finding or recalling the principles of science. 
In any given book they are often hidden, or it may be necessary 
to read several pages in order to obtain a single principle or 
fact. Truths of science are the most valuable tools one can 
possess for making scientific inventions. The inventor cares 
not how or when or by whom they were discovered. He cares 
for nothing except to kno^N them and then to use them. 

Note the two methods of procedure as set forth in the above 
principle and its corollary respectively at the beginning of 
this chapter. The principles are given in the following chap- 
ters. Scientific principles have another value to the inventor. 
They furnish him with that knowledge which will assist in 
making an invention, although the invention may not consist 
primarily of the combination of the principles used. They 
may sometimes enter in merely as elements of construction, not 
of invention. 

Because a certain principle or principles have been applied 
to produce a given invention, is no reason that they cannot be 
applied in a subsequent invention. Take, for instance, the 
principle that light blackens certain compounds. This formed 
the basis of the invention of photographs. Only recently it 
has been employed by W. C. Patterson (the invention being 
owned by the Walker Electric Meter Co.). He allows a ray of 
light to pass through an eye in a galvanometer needle and 
strike a moving paper covered with a sensitive photographic 
film. In this way he photographs the movements of the 
needle. The area within the curve, by calculation, gives 
the amount of energy for a given time consumed by lamps, 
motors, etc. 

In this book it would be useless to state absolutely every 
principle and fact of every department of science. Those of 
probable importance to the inventor are given. Those which 
have been applied once or twice, etc., are those which are most 
apt to be applied again, and certain old principles are known 
which have never been applied to any useful purpose. Out of 
all known electrical, physical, and chemical knowledge, those 
of maximum importance to the inventor have been formulated. 
An inventor can make scientific inventions without neces- 
sarily making discoveries. The scientific principles combined 
can be old. How fortunate this is ! The investigator studies 
the laws of nature and often spends a lifetime in adding only one 
or two new scientific facts or principles which may be appropri- 



30 

ated by the inventor. This rule of invention is not generally- 
recognized. The popular idea is that an invention is something 
radically new — new in every sense. Argument in the matter is use- 
less, provided the rule can be established by the proper analysis 
of important inventions. Several examples are given in order to 
prove that the rule is applicable in nearly every case. It is very 
seldom that the inventor both discovers and invents. He makes 
use of the scientific knowledge obtained by others. He uses as 
his tools old principles and facts — those which are open to all. 

The following analyses should be studied very carefully, and 
the inventor should analyze in a similar manner other inven- 
tions. The exercise is of great benefit as a preparation for 
solving problems. If he clearly comprehends any given prob- 
lem solved by others and clearly understands that it has been 
solved by the combination of old scientific principles or facts, 
and follows the combination step by step in order to discern 
the order in which they are combined, he will be better pre- 
pared to undertake new problems, and will not be so apt to 
travel in the indefinite footpath laid out by the popular mind, 
which seems to think that the invention is something new in 
absolutely every sense ; mysterious, due to inspiration, genius, or 
to some peculiar spirit which communicates the ideas without 
any preparation for, or attempts in, solving a given problem. In 
the analysis each problem is indicated by the name of the in- 
vention ; and the principles which were chosen and combined 
by the inventors are stated as briefly as possible. It is easy to 
assume and can often be proved that the inventor in each case 
combined many principles by twos and threes, etc., before he 
obtained the right combination, and that he obtained the desired 
results with other combinations, but that the commercial type 
was the best of them all. In short, let the inventor notice the 
probable truths : 

a. That the principles or facts combined were known in 
nearly every instance at the time the invention was made. 

b. That the device was easy to design and construct after 
the right combination was found. 

c. That the principles and facts are usually found not in one 
department of knowledge, but that a chemical fact is often com- 
bined with an electrical piece of knowledge, a heat principle 
with one or more acoustic, an acoustic with electrical, &c. 

d. That it follows that if past inventions have been thus 
made, it is reasonable to believe that future inventions may be 
made in the same manner. 

e. That the inventions would not have been made if the 
principles and facts had not been known. 



31 

/. And that in order to solve any given problem, the in- 
ventor need not expect to succeed until he has investigated 
scientific facts and principles with a view of obtaining the ele- 
mental and general results of a problem. 

Or he may combine principles hap-hazard to learn if a use- 
ful result follows. This last method of procedure is' the less to 
be recommended, because it is like a child writing promis- 
cuously the characters of musical notes, flats, sharps, &c., upon 
five parallel lines with the hope that a new tune will be com- 
posed. The way recommended is, first, to have some problem 
to solve. li there is no problem, what is the use of trying to 
invent ? It must be assumed of course by the author that the 
inventor has problems needing solution. Herein is a good 
place to distinguish the musician and poet from the inventor. I 
have seen them put on the same footing. They do not combine 
scientific facts and principles. They combine notes and words 
into bars and verses with no other object than to appeal to one 
or more of the senses or imagination. Instead of saying things 
in the ordinary way, the poet dresses up the words and sen- 
tences to appeal more forcibly to the longing one has of listening 
to the beauties of the particular language. A translated poem 
loses its charms, but an invention is useful independently of the 
nationality of the user. We hear of the musician and poet as 
being inspired, as having genius, and as being exceptional, and 
as succeeding not in proportion to anything except as to the 
amount of genius. It is held not to be similar with the inventor. 
He has a definite result he wishes to obtain; he must undergo 
the tedious and long work of seeking for and combining 
motions, principles and facts until he gets that combination 
which will solve the problem. With practice, this operation 
becomes very rapid. The reason of touching upon this compari- 
son is to try to overcome an old popular notion that an inventor, 
like the poet, must wait for the inspiration. He who believes 
in waiting is more likely to become a poet than an inventor. 
The analyses alluded to above are as follows : 
Incandescent Lamp or Subdivision of the Electric Current for 
Lighting. — An electric current is converted into light by its pas- 
sage through a conductor. The smaller the diameter, and the 
higher the specific resistance of the conductor, the greater the 
completeness of the conversion. Carbon has the highest specific 
resistance of all practical conductors, and is incombustible in 
a vacuum. Woody fibres, cotton and linen thread are car- 
bonizable at a high heat, whereby pure carbon remains having 
the same cellular structure as the original material. High re- 
sistances in parallel subdivide a current, so that a small portion 



32 

goes through each. Glass and platinum have the same rate, 
approximately, of expansion by heat, explaining why for so 
many years platinum has been used for making an electric con- 
nection from the exterior to the interior of a closed glass globe. 

Screw Propeller for Ships. — The rotary motion of a screw in 
a medium produces longitudinal motion, as illustrated by the 
well-known cider press. Experiment showed that this medium 
could be water. This illustrates the case of the mere applica- 
tion of a single principle. 

Thermo?neter. — Heat expands liquids proportionally to the 
temperature. 

Thermostat. — A rod made of two strips of different kinds of 
metal riveted together bends through an angle proportional to 
the temperature. 

Teslas New Phosphorescent Light. — The higher the potential 
of an electric current and the greater the frequency of alterna- 
tions of current, the greater the light during discharge. 

Telegraph Relay. — A very weak current may be concentrated 
by passing the same through a very long coil of wire wound 
upon a core of iron. Mechanical motion may be produced upon 
a delicately movable armature within inductive relation to said 
core. A powerful current may be caused to flow by the mere 
closing of a circuit needing only a very small force. 

Electrical Welding, — Heat is produced at loose contacts of 
metal in an electric circuit. The maximum heating power of 
an electric current is in a secondary coil of an induction coil. 
The coarser the coil in proportion to the fine primary coil, the 
greater the heating effects, assuming of course that the primary 
current is as great as practicable. 

Air Brake. — Friction may be produced and awheel prevented 
from rotating by means of a shoe pressed thereon by a spring. 
Air pressure, if sufficiently great, will overcome the force of the 
spring, reducing the friction to zero. Pressure of air may be 
diminished by allowing it to escape from its compressed con- 
dition into the open atmosphere. When air pressure is removed 
from a spring, the latter assumes its original pressure and 
produces friction upon the wheel. 

Kineiograph. — The phenakistoscope, invented years and years 
ago, during operation, shows to the eye in rapid succession 
figures of an animal, a man, &c., in different relative attitudes, 
producing upon the eye the effect of one figure having motion, 
in view of the persistence of vision. In this instrument, the 
figures are not made by photography, which in the case of the 
kinetograph are true to life if made at a high rate during the 
motion of any given object. 



33 

Telephone. — Speaking vibrates the air and membranes in 
unison with the larynx in the throat. A vibrating membrane 
always produces the same sound for the same vibrations. A 
vibrating iron membrane (armature) vibrates an electric current. 
A vibratory current vibrates an iron membrane in unison with 
the vibrations of the current. 

Siphon Recorder for Receiving Cable Dispatches. — A liquid 
charged with static electricity and located in an open capillary 
tube is expelled therefrom, overcoming the capillary attraction 
between the tube and the liquid. A paper surface moved past 
the stream of liquid, which may be ink, receives a line, whereas 
an ordinary pencil or pen would produce friction, which would 
take up more force to move the pencil than exists in the current 
which has traversed the sea. 

Chlorine Bleaching. — Chlorine has such a strong attraction 
for hydrogen as to take it from other elements, forming a gas 
which escapes into the air, the action being increased by the 
light of the sun. The coloring matter in fabrics is due to the 
presence of hydrogen, which, if removed, leaves the fabrics white. 

Direct Current Dynamo. — A closed conductor moved to and 
from a given current receives an induced alternating current. 
An alternating current is resolvable into a direct current by a 
pole changer acting in unison with the alternations. A direct 
current will energize a magnet. 

Davys Safety or Mifiing Lamp. — The temperature of a flame 
is, for any given oil, a certain degree. A metal introduced into 
the flime reduces the temperature immediately about the metal, 
where the flame becomes extinguished and unburnt carbon 
deposited, so that a fine wire gauze prevents a flame from pass- 
ing through the same and appearing on the opposite side. 

Gas Lighting. — Coal heated to redness out of contact with 
air generates carbonic mon-oxide C O, and carbureted hydro- 
gen C H4. These gases are combustible in air. 

Water Gas Lighting. — Water vapor in contact with red hot 
material is decomposed into hydrogen and oxygen, which are 
combustible, relatively. 

Forbe's Coulomb Meter. — A current heats a wire. A heated 
wire causes a rising flow of air. A mill is operated by moving 
air. Registering apparatus is operative by a windmill. 



34 
CHAPTER X. 

Acoustic Principles as Tools for Making Scientific 
Inventions. 



Speaking, singing, musical instruments and other sound 
producers vibrate the air, water or other medium. 

That against which the vibrations strike vibrates synchron- 
ously with the particular medium, and in unison also with the 
membrane in the throat or with the vibrating element of the 
sound producer. 

" Sound " (/. ^., air or other fluid vibrations) bounces away 
from a surface in the manner of a ball thrown against a house, 
except that the former moves in a straight line. 

Sound does not pass through substances in the manner of a 
bullet through glass, but the vibrations given to the glass set 
the air on the other side into vibration, thereby equivalently 
passing through the glass or other substance considered. 

Sound radiates in all directions from the sound producer. 

Sound may be concentrated upon a point by producing the 
sound at the larger end of a funnel or directly in front of a 
concave surface. 

When the smaller end of the funnel or a convex surface is 
employed the sound is scattered. 

Sound is louder the nearer the sound producer. If the latter 
is moved double the distance away, the sound is only one- 
quarter as loud. If the amplitude of vibrations is increased, the 
sound is proportionally increased. The denser the air, liquid or 
solid, the louder the sound. In the direction of the wind the 
sound is louder than in the opposite direction. The presence 
of a violin box or similar resonant body increases the sound. 
Sound is loud according to the degree of elasticity of the 
medium. 

A tube filled with air or water conducts sound so well that 
a sound can be multiplied several times. The larger the tube, 
the greater the length may be. If the tube is twice the diam- 
eter, the sound may be conducted twice the distance. 

Any given vibration of sound, whether vocal or instrumental, 
or from another source, has a velocity of i,ioo feet per second, 
at the ordinary temperature, and at the ordinary atmospheric 
pressure. In water the velocity is 5,000 feet per second. 

Metal conducts sound with a velocity of 16,000 feet persecond. 

A vibration of air consists of a condensniion and a rare- 
faction. The air is first compressed and under abnormal pressure. 



35 

and then it expands in the same manner as a solid rubber ball. 

Sounds vary in pitch, /. e.^ either high or low. The greater 
the number of vibrations, the higher the pitch, like a pendulum. 
The shorter the pendulum, the more rapid the vibrations. 

Loud or soft sounds have respectively greater and less 
amplitude, corresponding respectively to a pendulum of a fixed 
length, having a greater or less swing. This property is called 
intensity. 

Sounds also have quality, which varies according to the 
material which produces the sound. The sounds from violins, 
pianos, flutes and vocal organs come from different materials, 
and although of the same pitch, and intensity are of different 
quality. 

Sound added to sound increases, and sound opposing sound 
diminishes it. 

Air, while vibrated by sound, is as truly a form of mechanical 
power as a steam engine. 

Sound may be recorded visually, by placing the sound pro- 
ducer in front of a diaphragm provided with a point resting 
upon a moving surface of wax, tin-foil or other yielding 
substance. 

Sound cannot be bottled as water, but the records obtained 
as above will serve as a guide to the said point, so that by a 
repetition of movement of the surface the point will follow the 
record and cause the diaphragm to vibrate exactly as it did 
before, thereby causing the air to vibrate in unison and produce 
the sensation of the same sound upon the ear that was "stored" 
upon the surface. 

Sound may be classified as musical, articulate (speech), and 
miscellaneous. Articulate sounds differ from the others in the 
same manner that a continuous but irregular current differs from 
intermittent currents. 

An ivory ball dropped upon a stone bounces upward. A 
portion of the mechanical energy is converted into heat ; so also, 
in the case of sound, the condensations of air in vibrating pro- 
duce heat, and the rarefactions, cold. The condensations and 
rarefactions are the result of the sound, and are but another 
name for vibrations. 

The microphone does not magnify sound in the same sense 
that a microscope magnifies visible objects. The action is that 
a slight sound causes the carbon contacts to intermittently make 
and break a large electric current, which operates a telephone 
receiver, in the same manner that a relay opens and closes a 
local circuit, which furnishes the energy to transmit the message 
to double the distance first traveled by the message. 



36 

Neither does the microscope magnify light. It decreases it; 
because the magnified image is less bright than the object 
magnified. 

The ticking of a watch at the end of a long metal or wooden 
rod is distinctly audible, while through air at the same distance 
the sound is scarcely heard. Likewise the earth conducts sound 
better than the air. If the ear is applied to the rails of a rail- 
road, an approaching train is heard long before it can be heard 
in the air. 

All kinds of sound at a short range apparently travel with 
equal rate, because the music from a brass band is not confused; 
but those of greater intensity move most rapidly. In battles, 
those at a distance can hear the report of a cannon before the 
command to fire. 

The velocity of sound is the same whether traveling horizon- 
tally or vertically through the air; but it moves faster and faster 
from the source until a certain maximum is obtained. 

A bell heard through a tube 3,000 feet long is heard twice at 
an interval of over two seconds. The air conducts one sound 
and the metal of the tube the other. 

Wires are good conductors of sound. The scratching of a 
telegraph wire can be heard several miles, especially if the wire 
terminates in a membrane which terminates at the ear. Talking 
may be transmitted through a wire by stretching it from one 
membrane to another, and using them respectively as the mouth 
and ear piece. 

Since sound is reflected, it is badly conducted by a substance 
formed in layers or separated masses. Poor conductors are sub- 
stances like plaster, sand, porous earthenware, ashes and shavings. 

Echoes are sometimes heard by speaking against houses 
from a distance of 100 feet or more ; but they may be produced 
at any time by means of a concave reflector whose radius termi- 
nates in the speaker at anything over 100 feet. At this distance 
a one-syllable word is heard reflected. At 500 feet five syllables 
can be heard by reflection. 

Sound is reflected by clouds, also by the invisible aqueous 
vapor in the air. 

Lenses made of membranes between which is a liquid or 
gas concentrate or scatter sound as truly as ordinary lenses 
refract the rays of heat and light. 

The air may vibrate at any imaginable rate, but the ear can- 
not distinguish sound if the number exceeds 20,000 to 23,000 
per second, or is less than 16 to 8 according to the person ; for 
it is true that some persons can hear a high rate of 23,000 
vibrations per second, while another hears it not. 



37 

The louder the sounds, the higher the note which is audible. 
With weak sounds the ear cannot hear a note having over about 
10,000 vibrations per second. 

If several clocks are placed upon a shelf, their pendulums 
will soon vibrate in unison, although previously they were 
vibrating differently. 

A tuning fork, scarcely audible, if placed upon a board, or 
a piano, is audible several feet away. The piano having a large 
surface, sets a large mass of air into vibration, and therefore the 
increased loudness. 

If a tuning fork is operated in front of a small hole in a hol- 
low body (resonator), the air inside will or will not loudly 
resound according to the volume of the enclosed air. If 1,000 
tuning forks of different pitch are employed, the resonator will 
answer to only one fork. 

The mouth is a resonator for the sounds produced by the 
larynx, and answers to all notes sung, because the shape and 
size are made to change by the different positions given to the 
lips, cheeks, teeth, tongue and jaws. 

The longer the string in a piano, the lower the note. Men's 
voices are of lower pitch than those of women, because the 
vocal strings are longer in the former. 

Sound produced by a tuning fork is simple — there is only 
one rate of vibration. That produced by strings is compound, 
and consist fi-rst, of one set, giving the note proper ; secondly, 
the harmonics, which arise from vibrations of a different rate. 
The following analogies will explain: A rock dropped into quiet 
water is like a tuning fork, producing one large set of waves, 
but no small one. Immediately after the rock is thrown, cast in 
some smaller stones of different sizes. Little waves are visible 
upon the large waves, illustrating to the eye how vibrations of 
different rate and amplitude can coexist. 

If vibrations of two sounds having vibrations of equal length 
are in the same phase, the sound is doubled ; but if one vibra- 
tion is half way behind the other, no sound is heard. If the 
vibrations are of different lengths, the sounds tremble, /. ^., are 
alternately loud and soft. 

A gas flame sings when located within a tube open at both 
ends. Some of the air is consumed, making a rarefaction ; then 
more air rushes in, causing a condensation, and so on in such 
rapid succession as to produce a note. The gas for the flame 
should issue from a finely drawn tube projecting upward from 
a gas pipe. This tube should extend into the first-named tube. 

A plate fastened at its centre may be vibrated by a violin 
bow drawn across its edge. If sand is placed upon the plate it 



38 

forms into fanciful figures, according to the point of application 
of the bow. The plate may be fixed at the edge and the bow 
drawn against the edge of a central hole. A membrane stretched 
and held by its edges and vibrated by blowing a whistle or by 
other sounds arranges sand, placed thereon, in regular figures. 

Sounding bodies sometimes attract and sometimes repel other 
bodies. The sounding body is conveniently a violin. A balloon 
of carbonic acid gas is attracted toward the opening in the box; 
one of hydrogen is repelled. 

Suspended and neighboring tuning forks attract each other. 
A piece of paper suspended by a silk thread and near a sound 
producer is attracted thereto ; or a card may be fixed and a 
sounding tuning fork suspended near it. A flame is repelled by 
an adjoining sounding body. 

Small resonotors, made for instance of small pasteboard 
boxes, containing each a small hole and mounted upon cross- 
arms pivoted at the centre, revolve about the pivot when a 
sounding box is located sufficiently near. 

The graphophone differs from the phonograph in that in the 
latter the record on the wax occurs as indentations, while in the 
former curves are marked parallel with the surface of wax. 



CHAPTER XI. 

Principles in Heat and Light as Tools for Making 
Scientific Inventions. 



Heat and light vibrate the molecules of a body ; — sound 
vibrates the body as a mass. 

Heat has the power of converting solids into liquids; liquids 
into gases; changing the color of metals, as by making them 
red hot, producing electric currents; effecting chemical re- 
actions; producing sound; overcoming magnetism; and develop- 
ing mechanical motion. 

Light may be converted into heat, electricity, magnetism; 
and it will produce chemical decomposition and mechanical 
power. 

Heat and light act in opposition to that of cohesion, as 
illustrated by its converting a solid into a gas; the volume of 
the gas being greater than that of the solid. 

Heat, in vibrating the molecules of an animal's body pro- 
duces a sensation which is also called heat; but science uses 



39 

this term to indicate the vibration of the molecules of a body 
or of that of the medium between bodies, said medium having 
the property of communicating heat from one body to another. 

When two bodies of different temperatures are brought 
together, the motions of the molecules of the one are communi- 
cated to those of the other, which becomes warmer; finally the 
molecular motions of both are communicated to surrounding 
objects, until reduced to the normal condition. 

In a manner somewhat similar to sound being communicated 
from one body to a distant one by vibration of intermediate 
air, so heat and light are assumed to be communicated by an 
atmosphere so thin and light that it cannot be detected by any 
present known means. 

Heat and light are not intercepted by a vacuum; but sound 
is cut off. 

Solids, liquids and gases differ from one another because of 
the relative positions and motions of the molecules. 

In gases, the heat has entirely overcome the force of cohe- 
sion; so that the distance between the molecules depends only 
upon the pressure of an external medium and upon gravitation. 
At a thousand miles above the earth the molecules of the air 
are probably many feet apart. 

In solids, the molecules vibrate within fixed limits; and 
when moved beyond those limits by mechanical force the body 
is divided into separate masses. 

In liquids, the forces of heat and cohesion are nearly bal- 
anced, and remain so between fixed temperatures under any 
given atmospheric pressure. 

In solids, the distance between the molecules is less than in 
liquids, and less yet than in gases. 

A vapor is an intermediate state between a liquid and 
gas. The forces of cohesion and heat are more nearly balanced in 
a vapor than in any other form. A slight reduction of temperature 
or increase of pressure causes liquefaction. A slight elevatioti 
of temperature or decrease of pressure causes gas. 

Some solids have the property of vapors, in that they are 
convertible directly into a gas by heat without first becoming a 
liquid. 

The molecules of an enclosed gas strike upon and rebound 
from the inner surface of the containing vessel; the resultant of 
all the forces being pressure which is increased by heat. If the 
gas is enclosed in a yielding vessel, as of rubber, the volume of 
the vessel increases by heating. 

The volume of a solid or liquid likewise increases by heating 
and diminishes by cooling. 



40 

What is true of light is true of heat, because light is usually 
heat; but what is true of heat is not necessarily true of light, 
because heat exists without light. 

The sum of the forces exerted upon a surface by the mole- 
clues of a gas results in a constant resultant pressure. 

In order to show the rapidity of vibrations of molecules, it 
has been proved that the number of impacts, in a second, of a 
molecule of gas upon a surface is 4,700 millions. The length of 
the path of the molecule at ordinary temperature and pressure 
is in length equal to .000000095 of a yard. The diameter of a 
molecule of hydrogen is approximately .0000000008 yard. 

Heat produces three effects upon a body. i. It increases 
the volume. In doing this, it overcomes the pressure of the 
atmosphere or other surrounding fluid. 2. It increases the rate 
of vibration, which is the cause of rise of temperature. 
Work is expended to do this in a manner similar to work being 
expended in increasing the number of vibrations per minute of 
a cannon ball or of the piston of a steam engine. 3. It in- 
creases the swing or amplitude of the vibration. Work is there- 
fore expended, as in the case of a piston; the further it is moved, 
the more the energy expended. 

Of solids, liquids and gases, the same are expansible by heat; 
gases, most; solids, least; and liquids, at a medium rate. 

The expansion maybe mostly in one direction, as with a rod; 
in two directions, as in a sheet; or in three directions, as in a 
cubical block. 

The temperature of a body corresponds to the pressure of a 
liquid or to the electromotive force of an electric current. A 
thimbleful of water may have the same temperature as a 
barrelful. 

The expansion of solids, liquids or gases is proportional to 
the temperature; /. e. to the rate of vibration of the molecules. 

A globule of mercury or other liquid in a fine tube is moved 
considerably by heating the air in a bulb formed on the end of 
the tube. The air expands and drives the globule along the 
tube. 

A fine evacuated capillary glass tube is acted upon gradually 
by the pressure, so that after a year or two the diameter of the 
tube is less. 

Different kinds of substances have different degrees of ex- 
pansion under the same amount of heat. 

In a similar manner that a short magnet is more quickly 
magnetized and demagnetized by an electric current than a long 
magnet; so does a thermometer mercury column change more 
rapidly in length the smaller the bulb thereof. 



41 

Increase of density in any given substance increases the 
rate of expansion per unit of heat. 

Among familiar substances, the following solids are more 
and more expansible by heat in the order named: Diamond, 
wood, graphite, compound minerals, glass, platinum, steel, iron, 
copper, lead, ice, gutta-percha. 

The sources of cold and their degrees are: — mixed bisulphide 
of carbon and nitrous acid — 140° C; ether mixed with the vapor 
of carbonic acid when liberated from the confined liquefied car- 
bonic acid — 110°; Arctic regions — 58°; liquefying of mercury 
from the solid state — 40°; mixture of snow and salt — 20° 

Red heat of metals is obtained at 550°. Fusion of silver, 
i,ooo°;.of cast iron, 1,530°; of platinum, 2,000°: blast furnance, 
1,800°. 

The heating of one side of a long rod causes that side to 
expand, while the other side remains cool for a while; conse- 
quently the rod bends. If the rod is made of different metals 
the rod will bend when heated, because one metal expands more 
than the other for any given amount of heat. 

Heat may be made to break thick glass by heating one side 
and cooling the other. 

Through the expansion of bodies heat becomes a form of 
mechanical energy. 

Heat varies a current in expanding a rod pressing upon car- 
bons touching one another while forming a part of an electric 
circuit. The more the rod is heated, the closer the carbons 
come in contact, and consequently the greater the current. 

Non-crystalline substances expand by heat, equally in all 
directions. With certain crystals the expansion is not the same 
in all directions. 

A substance besides that of type metal, which contracts 
upon heating and expands on cooling, is argentic iodide. 

Independently of the kind of gas, whether air, hydrogen, 
chlorine, coal gas, or any other gas, the amount of expansion 
for the same amount of heat is approximately the same. 

Metals become just visibly red at 525° C; dull red, at 700°; 
cherry color, at 900°; orange, at 1,100; white, at 1,300°; brilliant 
white, at 1,500°. 

A gas will pass through platinum at as high temperature as 
through porous earthenware, but not to such a degree. 

When a solid is heated sufficiently to approximately over- 
come the force of cohesion, it becomes viscous or liquid, accord- 
ing to the nature of the substance. 

The temperature for fusion is different with different sub- 
stances. The following are some illustrations: Ice fuses at 



42 

o° C; phosphorus, at 44°; wax, at 65°; fusible metal, at 68°; 
sodium, at 90°; sulphur, at 114°; lead, at 335°; aluminium, at 
850°; and platinum, at 1,775°. 

Heat applied to solids increases the temperature, but as 
soon as fusion begins the temperature remains constant until 
the whole solid has been converted into a liquid. 

The same principle is true in regard to the conversion of a 
liquid into a gas. 

Glass and iron are examples of those solids which pass 
through all the stages of viscosity before becoming a true and 
thin liquid. Of such substances the melting temperatures are 
all the temperatures between those at which viscosity begins 
and ends. 

The melting point may be raised by increasing the atmos- 
pheric pressure upon the substance heated. 

Generally, an alloy of metals fuses at a lower temperature 
than any of the metals composing it. 

A mixture of a metal and non-metal usually fuses at a lower 
temperature than the metal. Steel (containing infusible carbon) 
melts at very much lower temperature than iron. 

The principle is true generally for non-metals. Sodic and 
potassic chlorides, when mixed, fuse at a lower temperature than 
either when alone. 

Heat may be stored by converting a solid into liquid or 
liquid into gas; when the gas becomes a liquid again or the 
liquid a solid, the same amount of heat is given out. 

Equal quantities of ice and hot water intimately mixed are 
found to assume a temperature of 0° before the ice is all melted. 
This water at zero mixed with an equal quantity of water at a 
higher temperature results in water at an average of the two 
temperatures. 

Most solids may become liquefied not only by fusion, but by 
solution. Common salt for instance fuses at a comparatively 
high temperature, but at any temperature above 0° it may become 
a liquid by solution in water. Some substances, practically in- 
fusible, are convertible into a liquid by solution. Solids which 
are opaque often become transparent by solution. 

A liquid is limited in its capacity of dissolving solids. After 
a certain amount has been dissolved, any additional amount 
remains undissolved, unless the temperature is increased. The 
temperature of a liquid is decreased during the process of 
dissolving therein a solid. 

If the solid and liquid enter into chemical combination, the 
temperature increases, decreases, or remains constant, according 
to the nature of the substances. With cold quick-lime and 



43 

water (whereby the new substance, calcic hydrate, is formed) the 
mixture becomes very hot. The two substances combine to 
form a new compound. Where no chemical combination 
occurs the temperature lowers. Where the heat produced by 
chemical action is equal to the cold produced by conversion of 
a solid into a liquid, the temperature remains the same. 

Heat is the force which determines crystallization, which may 
be obtained by solidifying bodies by slowly evaporating the 
liquid from their solution or by slowly solidifying from a state 
of fusion. 

Water containing no air in solution freezes at 15° lower 
temperature than water in which air is absorbed. The water 
should be kept very quiet. Air may be removed from water by 
long boiling. 

Violent agitation of a liquid at a freezing point prevents 
solidification. 

When strong salt water freezes, the ice is practically pure. 
Of solids and liquids of the same substance, the latter are 
greater in volume. Certain substances heretofore named are 
exceptions. 

Water expanding on solidification is thought to be due to 
the fact that the crystals occupy more space than if it 
solidified without crystallization. When the crystals melt, 
the mobile liquid fills up the space formerly left between 
the crystals. 

Certain substances, as gelatine and gum arable, do not lower 
the temperature of water while dissolving. 

Sodic iodide, at a slight additional pressure of atmosphere, 
boils while melting. 

Any liquid at any temperature boils in a vacuum. To main- 
tain the boiling, the vacuum must be maintained. 

The vapors of liquids relatively insoluble produce double 
the pressure of either; those more or less soluble in each other 
exert less than double the pressure of either. Place water and 
benzole in an enclosed space. The pressure is double that 
which either the water vapor or benzole vapor would give 
alone. 

Connect two vessels containing respectively ice water and 
hot water. The pressure of the vapor in each is the same as that 
which would exist in the cooler vessel if the other were absent. 
This principle holds true with all vapors. 

The rate of evaporation varies with the temperature, the 
amount of vapor of the same liquid in the atmosphere, the sur- 
face of liquid exposed, and the changes in the nature of the 
surrounding atmosphere. 



44 

The following are the boiling points of some important 
liquids: — water, ioo° C; mercury, 358°; melted zinc, 940°; 
benzole, 80°; alcohol, 39°; liquefied nitrous oxide, 92°. 

The boiling point is higher in case the liquid contains solid 
substances in solution. Concentrated salt water boils at 202° C. 
The boiling point is lowered if the liquid contains gaseous or 
volatile substances in solution. 

Water covered with a film of sweet oil boils at a higher tem- 
perature than when not so covered. A slight explosion occurs 
when the temperature reaches 120° C, and then the liquid boils. 

Water boils in glass vessels at 106° C, and in metal vessels 
at 100°. A piece of metal placed in the glass vessel makes the 
water boil at 100°. 

Water boils at lower and lower temperatures, the further 
upward it is moved from the earth. 

Water cannot be boiled in an enclosed vessel except at a 
very high temperature when it turns immediately into steam. 
Remove air from water by ordinary boiling. Place a little of 
the water in a thick sealed glass tube. Heat to 200° C. The 
water instantly disappears. The experiment is of course 
dangerous, as the pressure is 500 lbs. per sq. in. 

In an enclosed space containing air a vapor will enter, in the 
same manner that sugar will enter water. In other words a gas 
will dissolve a vapor. The pressure within the vessel will be in- 
creased the same as if the vapor were entering a vacuum. 

A liquid assumes a globular form when dropped upon a hot 
surface (above the boiling point). The globule rests upon a 
cushion of the vapor of the liquid. As soon as the temperature 
of the plate falls to that which allows the globule to be in actual 
contact with the plate, the globule bursts violently into steam. 
The temperature of the globule is below the boiling point. Upon 
the same principle, men have been able without injury, to 
plunge their wet hands into melted lead. 

Water in a porous vessel grows colder. The evaporation at 
the surface produces the cold. 

A liquid may be separated from another liquid, as ether 
from alcohol, by heating to the boiling point of the more volatile 
liquid (ether) which passes into a receiver, while the alcohol re- 
mains behind. Similarly, a gas may often be liberated from a 
solid, even if chemically combined therewith. Coal gas may 
thus be separated from coal. 

By high pressure and low temperature, a gas, even air, car- 
bonic acid, and ammonia, may be converted into a liquid. 
Oxygen in liquid form is colorless and transparent, and in 
evaporating has a temperature of — 181° C. 



45 

Partially fill a metallic vessel with water. Add ice and a 
thermometer. The temperature falls. At a certain temperature 
dew will immediately form upon the vessel. 

Some good absorbents of moisture from the air are phosphoric 
anhydride; quick-lime; strong sulphuric acid; calcic chloride 
and cobaltic chloride. Paper saturated with the latter, dried, 
and then put into damp air turns from blue to pink, and when 
taken to dry air becomes blue. Heat will also turn it blue. 

If a thermometer bulb is wet with water, alcohol, ether, &c., 
the temperature falls in proportion to the dryness of the air. 

Hair has the property of lengthening considerably by absorp- 
tion of moisture. Twisted catgut strings untwist when moist 
and twist while drying. Similar actions occur with paper 
coated on opposite sides respectively with gelatine and varnish. 

Radiated heat can be transmitted through a medium with- 
out appreciably increasing the temperature. 

Light is not conducted by a substance, but heat is. If lumi- 
nous paint is exposed in parts to light, the parts not exposed 
give no light in the dark. If light were conducted in the man- 
ner of heat, the paint would appear equally luminous in the 
dark. Many substances, as glass, will allow light to pass through 
the same, but the light is not conducted in the same sense as 
heat. 

As with electricity, so with heat, substances have different 
conductivities. The best conductors of heat are usually the 
best conductors of electricity. 

Different substances conduct heat at widely different veloc- 
ities; and electricity is conducted by different substances at 
approximately the same velocity. There is a difference in the 
electrical velocities, but it is scarcely detectible for ordinary 
distances. 

Heat is conducted in wood better in the direction of the 
fibre than transversely. 

The mixed double mercuric and cupric iodide under the 
influence of heat turns from bright-red color to dark purple. 

Copper is loo times a better heat conductor than water. 

Water becomes heated principally by circulation. One part 
becomes heated. It rises like a cork and the cold water takes 
its place, and so on until the whole mass is heated. For this 
reason the heat should be applied at the bottom. Alcohol may 
be burned on the top of water, and yet just below the surface 
the water is cold; showing that water is a very poor conductor 
of heat. Gases conduct heat even less than water, but they 
will allow heat and light to pass through. Liquids become hot 
by the process of circulation, as in the case of water. 



46 

Heat is communicated from one body to another with a rate 
dependent upon the number of points in contact. The maxi- 
mum amount is conducted in any given time by having very 
smooth surfaces of contact. 

Rays of heat and light are projected from a body equally in 
all directions, and lie in straight lines. 

Rays of light and heat may be bent by allowing them to pass 
obliquely from any given medium, as air, into a denser medium, 
as glass, or a rarer medium, as rarefied air. 

From any given mass heat and light are radiated in direct 
proportion to the amount of radiating surface; and according 
to the color. They are radiated best from a rough black sur- 
face, as made with lamp-black. 

Both heat and light, like sound, are reflected from a sub- 
stance. Not all is reflected ; a portion is absorbed by the 
substance. 

The angle at which the heat and light are reflected is equal 
to that at which they fall upon the surface. Echoes are re- 
flected sound. The surface reflecting the sound seems to origi- 
nate the sound; similarly, a white house seems to be the source 
of light; whereas the light coming from it is reflected light. 

The rays of reflected light and heat are in the same plane as 
those which fall upon the surface. 

Reflected heat and light may be reflected repeatedly and in- 
definitely, but a fraction disappears each time by absorption. 

A bright concave surface brings the rays of light and heat 
to a focus; a convex surface scatters them. 

In the highest attainable vacuum heat and light are reflected 
as well as in the open air; and in compressed air as well as in 
air at the ordinary atmospheric pressure. 

The cold rays from ice or similar substance, when focused, 
reduce the temperature of that which is placed in the focus. 

A flame radiates little heat in proportion to its high tem- 
perature; but an incombustible mass, as platinum, placed in the 
flame causes a large increase of radiated heat. 

A ray of heat or light is a series of vibrations. In a ray of 
sound the vibrations travel about i,ioo ft. in a second; in the 
case of heat and light, the speed is such that only about eight 
seconds elapse in the transit of a vibration from the sun to the 
earth — 93,000,000 miles. 

Sound vibrates the mass; light and heat vibrate the mole- 
cules of the mass. 

In the same sense in which the ear does not distinguish 
sound if the vibrations are above or below a certain rate, so the 
eye does not distinguish light below or above a certain rate of 



47 

vibration. There are 3,000 nerves from the ear to the brain, all 
tuned to as many different sounds. The shortest respond to the 
highest notes; the lowest to the lowest notes; so also, in the case 
O' the eye, there is a power of seeing only when the number of 
vibrations is within certain limits. 

An electric crurent at the instant of rupture or closing, in 
circuit with one's head, causes the nerves of the eye to vibrate 
in unison with the vibrations of the current, so that in the dark 
a slight flash of light is produced, but no object becomes visible. 
Three Leclanche cells of ordinary size will not injure the eyes. 
The flash appears as if one were winking. 

Let a body be heated from 0° C. to an indefinitely high tem- 
perature. The emitted heat vibrations are added to by more 
rapid vibrations as the temperature rises. The first vibrations 
visible occur at such a rate as to produce the sensation of red. 
Violet rays are due to the most rapid of those which produce 
sensation of light. Chemical effects are produced by rays 
which have a higher rate than those which produce violet and 
by violet rays also. 

If a ray of light (which is accompanied by heat) falls upon a 
three-sided piece of transparent substance (called a prism) and 
strikes a surface in an otherwise dark room, the vibrations of 
the ray are separated from one another, occupying a long rec- 
tangular area, when projected upon a surface. 

Violet is seen at one end and red at the other. Just beyond 
the violet, where no light is visible, exist chemical rays, because 
they will turn photographic paper black and produce other 
chemical actions. Just beyond the red, where no light is visible, 
a thermometer indicates heat. Throughout the limit between 
red and violet are heat, light and chemical rays. The strongest 
heat rays are at the red; the strongest chemical rays at the 
violet; and the strongest light rays at the yellow. The combi- 
nation of all the color rays forms the original white sun- 
light. 

The seven colors may be combined by reflecting each 
by a mirror, so as to strike all at the same spot. The spot 
appears white. Lenses may also be employed to combine 
the rays. 

The seven colors, violet, indigo, blue, green, yellow, orange^ 
red, are simple and cannot be analyzed; but two or more can be 
compounded to form other colors. 

The above principles teach what is otherwise found to be a 
fact, that an incandescent body, as the sun, radiates simul- 
taneously vibrations of different rates, and that they do not 
interefere with one another 



48 

A bright object is visible after it has been placed behind an 
opaque screen. This is due to the fact, that an image formed ir 
the eye remains after the object is removed. Let a disc bt 
painted with the colors of the rainbow arranged as the pieces o 
a pie when cut. If the disc is rotated rapidly it appears white 
The colors mix in the eye. Before one color disappears fron 
any given spot the others overlap. 

If the red and green and yellow of the spectrum are reflectec 
by mirrors upon a given spot, white light is produced. Com 
pounded green, yellow and violet produce white; also orang( 
and blue. Colored pigments cannot be used, as they are absorb 
ents of colors. Mixed yellow and blue paints produce green 
and so on with greatly different results from those obtained b] 
mixing spectral colors. 

Light produced by combustion is seldom simple. Th« 
yellow light of the gas flame contains blue, red, orange, &c 
Common salt burned in alcohol gives nearly a pure yellow light 
Roses have no color, because no red is present in such a flame 
A man's face looks deadly pale in such a light. 

Pure red is obtained by passing daylight through glas 
colored with cuprous oxide; pure blue by passing through 
solution of cupric sulphate, and pure red by passing dayligh 
through a solution of ferric sulpho-cyanide of iron. 

Rock salt, I inch thick, transmits 92 per cent, of heat; smokin 
quartz, 67; glass, 39; alum, 12; ice, 6; and cupric sulphate, none 

Heat is largely "lost " in its passage through glass; but th£ 
which has passed through, passes through a second piece c 
glass with practically no loss. When alum and rock salt ar 
superposed they are opaque to light and heat. 

If I represents the amount of heat absorbed in its passage 
through air, i , 200 represents the amount absorbed by ammonia gas. 

If a gas is allowed to rush into a vessel both become heated, 
because the molecules of the air strike against the side of the 
vessel, whereby the force of motion is partially converted into 
the force of heat. 

When a gas is rapidly exhausted from a vessel, cold is pro- 
duced, because the heat produced in the manner above stated 
is converted into motion. 

The best absorbents of heat are the best radiators. 

Elementary gases, as hydrogen, oxygen, &c., are worse 
absorbents of heat and light than compound gases, like carbonic 
acid, coal gas, &c. 

White substances absorb the least and black the most light 
and heat. An exception is that of plumbic carbonate (white 
lead), which absorbs heat as fast as lamp-black. 



49 

Snow covered by some black substance melts faster than 
^hen bare. 

Drops of water often cause the surface under the same to 
mm when both are exposed to sunlight. The drops absorb 
he heat and at the same time focus it upon the surface, because 
he drops have the shape of a lens. 

Rock salt covered with lamp-black, or with iodine stops light, 
)Ut transmits heat. 

A hothouse becomes warm because the light reflected from 
)bjects within is reduced to polarized and heat rays to which 
jlass is opaque. 

Of any different substances absorbing heat one will increase 
n temperature faster than the other. They both are exposed 
o the same heat, but the temperature of the one rises faster than 
hat of the other. Mercury rises in temperature much more 
apidly than water. The former is said to have a higher specific 
leat than the latter. 

The specific heat of any substance, when liquid, is higher than 
i^hen solid. Water will get hot about twice as fast as ice. 

The figure denoting the specific heat indicates how many 
imes more heat is required to raise the temperature of the sub- 
tance through i° than to raise the temperature of water i°. 
The atomic weight indicates how much heavier an element is 
han hydrogen. The product of the specific heat and atomic 
weight of any elementary substance is approximately a constant 
_uantity, and equal to about 6. 

Rubbing or pressing substances together produces not only 
^atic electricity, but also heat and sometimes light. 

All substances, even ice, have heat, and it is believed that 
absolute cold has never been obtained; but that it would exist 
only when the molecules are so close together as to be incapable 
of motion. 

Other sources of heat are the sun, electricity, chemical 
changes, those bodies which are warmer than the thing to be 
heated, percussion, terrestrial heat, absorption and animal 
heat. 

Heat produced by friction is greater, the greater the rela- 
tive motion and pressure. 

Pieces of ice rubbed together in a vacuum melt. 
Water shaken is increased in temperature about i°. 
Flint rubbed against steel detaches steel particles which are 
so hot as to burn with scintillation. 

The movement of shooting stars through the air at their high 
velocity causes so much heat that they burn at a white heat, 
the same being invisible before reaching the earth's atmosphere. 



50 

A tube filled with water and rapidl)'' rotated between two 
sticks may be made to boil. 

The temperature of a body rises in a certain proportion to 
the increase of its density. Air compressed in a tube by a piston 
becomes heated. 

Shot fired against an iron mass produces light visible at 
night; showing that mechanical motion is converted into heat 
and light. Iron when hammered becomes hot. In general, 
percussion, as well as friction and pressure, produces heat. 
Lead is not increased in density by, but becomes hot upon, 
hammering. 

The amount of heat received by the earth from the sun 
in a year is capable of melting a coating of ice upon the surface 
of the earth j6o ft. in thickness; which is .0000000005 part of 
the total heat of the sun. 

By descending into the earth 30 yards (more or less according 
to the location) the temperature remains constant during sum- 
mer and winter. The heat is independent of the sun and is due 
to a source of heat within the earth. 

Upon approaching toward the center beyond 30 yards the 
temperature increases; about 1° for every 90 feet. At a depth of 
30 miles the temperature would be sufficient to melt all known 
substances. The amount of heat received at the earth's surface 
from the internal heat is .0001 that received from the sun. 

Substances become warm while absorbing gases. Platinum 
becomes so hot by absorbing oxygen gas that a stream of 
hydrogen passed over the same ignites. While charcoal absorbs 
gases its temperature is increased. 

If chemical actions are slow, heat is scarcely perceptible. 
The same chemical actions, when rapid, apparently generate a 
larger amount of heat. Wood, while decaying, gives off the 
same aggregate heat as the same quantity of wood burned in a 
fire. 

All ordinary combustion is obtained from the union of the 
oxygen of the air with the substance burned. 

Luminosity does not depend upon temperature. 

Phosphorus when rubbed emits light. An alcohol flame, 
almost non-luminous, is of much greater temperature than that 
of a candle flame. 

Hydrogen and oxygen when burning give no light, but give 
the hottest known flame. 

Luminous paint, placed in sunlight and removed to a dark 
room, gives light for hours, but its temperature is not abnormal. 
Diamonds and a few other substances have this property of 
luminous paint. 



61 

Fire-flies give much light, but practically no heat. 

The amount of heat produced by hydrogen burning in 
oxgyen is 17 times greater than that of wood in oxygen; while 
the light in the former is practically zero. In the Geissler tube 
light is produced without heat, but the luminosity is too little 
for commercial use. 

Although charcoal, graphite and diamond are all pure car- 
bon, yet the combustion of each gives a different quantity of 
heat; but the quantity is the same in the aggregate if the 
densities are taken into account. 

In an animal the force of chemical affinity is converted into 
mechanical motion. The oxygen taken in at the lungs and the 
food at the mouth undergo chemical changes, which are repro- 
duced in the forms of heat and motion. 

Oxygen unites with carbon to form carbonic acid in animal 
life. In vegetable growth the carbon is taken from the carbon, 
liberating the oxygen. The oxygen which is consumed by 
animal life to form carbonic acid is liberated by plants which 
take the carbon only. 

Oxidation of iron, wood, &c., produces heat. Oxidation of 
the iTiuscles produces mostly contraction of the muscles, but 
little heat. 

Plants store heat during growth and give it out during decay 
or combustion. An exception is at the time of blossoming. 
Oxidation then occurs and the temperature of the plant rises, as 
in animals. 

The temperature of a flame is increased by increasing the 
rapidity of the supply of oxygen. 

Highly compressed air allowed to exit into the air on a 
summer's day produces a shower of snow-flakes. 

Compressed air escaping upon a thermopile in circuit with 
a galvanometer deflects the needle in one direction, while air 
from a bellows deflects the needle in the opposite direction. 

A pin-hole in paper or other thin membrane acts as a lens in 
a camera. An image of an object in the light formed in the 
dark is inverted. 

Light vibrations have an actual velocity about 185,000 
miles per second. 

The brightness of a surface exposed to light radiating from 
a luminous point is quartered when the distance is doubled. 
Heat, light and sound vary inversely as the square of the 
distance. 

If a surface is inclined to a ray of light the brightness 
varies with the cosine of the angle. Cosines of angles are found 
explained in books on trigonometry. 



52 

A grease spot on paper practically disappears when equally 
illuminated from opposite sides, but grows darker and darker, 
the greater the difference of brightness on opposite sides. 

The intensity of sunlight is 670,000 candle-power. 

Light travels in a straight line, but may be bent by allowing 
it to pass obliquely to or from a denser or rarer medium, or to 
be reflected at an angle from a mirror. 

A ray of light, as a whole^ may be vibrated by rapidly inter- 
rupting the same by an opaque object, by vibrating a mirror; by 
varying the medium through which it passes; by vibrating a 
lens or prism which transmits the light; or by a combination of 
two or more of the above means. 

A ray of light may be regulated as to intensity and quantity 
by any of the means named for vibrating it. 

The image formed by one lens or reflector may be made 
larger by a second lens or reflector. Light is magnified by con- 
centrating to a focus, as is the case with heat and sound. 

The light from stars is bent and re-bent, and reflected by 
entering the denser atmosphere about the earth, and conse- 
quently the appearance of " twinkling." 

A substance appears red because it absorbs all the other 
colors composing white light and reflects only red. In a 
similar manner substances appear blue, green, yellow, &c. 

Red glass is red by transmitted light, because red passes 
through the glass while other colors are reflected or absorbed. 
So with glass of other colors. 

Colorless glass is that which transmits all the colors. 

A red object, as a rose, has no color in a room where 
only blue light exists, and so also with a green object in light of 
a different color. Although a gas, candle or oil flame has a 
yellow appearance, yet nearly all colors exist. The yellow is in 
excess. So also, some bodies appearing of a certain color re- 
flect other colors, which are not visible, because overshadowed 
by the prominent color. 

Place paper of one color upon paper of a different color. 
Fix the eyes upon the same, and jerk the top paper away. The 
remaining paper has a color different from either. The papers 
should be in daylight and the time of observation about one 
minute. The color of the top paper remains in the eye after re- 
moval and mixes with the color from the bottom paper, form- 
ing a color composed of the two colors. 

The spectrum is the name given to the heat, light and 
chemical rays eminating from a source of heat and light, after 
analysis by a prism. The heat rays are slowest in vibration 
and the chemical most rapid, while light rays are medium. 



53 

Anything which will reduce the rate of vibration of chemical 
rays will convert them into light rays ; and similarly light rays 
would be converted into heat rays. 

The sulphides of barium, calcium or strontium, commonly 
called luminous paint, give off blue light when placed in the 
chemical rays, which are otherwise invisible. The rate of vibra- 
tion in the chemical rays is reduced to that of bluish light. The 
color varies with the temperature of the sulphide and whether 
the sulphide of barium, calcium or strontium is employed. The 
last named at 20° C. is violet; at 40°, blue; at 70°, yellow; at 
100° (boiling point of water), orange; and at 200°, almost in- 
visible. The light is emitted without extra heat. It may be 
called cold light. 

The maximum time of luminosity of luminous paint is 30 
hours. 

For a few seconds or fraction of a second the following 
substances possess similar properties of luminious paint : 
Diamonds, amber, milk sugar, cane sugar, dry paper, silk, Ice- 
land spar, uranium compounds. By means of a special instru- 
ment called a phosphoroscope the last-named substance is 
caused to become visible in a dark room .04 second after ex- 
posure to light. It has a higher candle-power than luminous 
paint, but lasts only the above fraction of a second. Many sub- 
stances are not phosphorescent. For example, phosphorus, 
after which the property is named. Phosphorus appears light 
in the dark, simply because it unites with oxygen. It is not 
light in a vacuum, nor does exposure to light have any more 
effect than darkness. Other non-phosphorescent substances 
are liquids, metals, quartz and sulphur. 

By heating diamonds, or the mineral chlorophane, to 300° C. 
(red heat of metals being 525°), the same become luminous 
and remain so for several days, although the temperature falls 
to the ordinary degree of the atmosphere. 

Light stored by luminous paint is increased by heating ; but 
the luminosity lasts for a proportionally less time. 

In the same manner that phosphorescent substances con- 
tinue to vibrate in unison with light rays, so do many bodies 
continue to radiate heat when taken from a source of heat, and 
generally the molecules of all bodies are in continual vibration 
or else absolute cold would exist. 

When a source of heat, light or sound rapidly approaches a 
person, the vibrations are more numerous per second ; and 
when moving away, less frequent. Illustration: An approach- 
ing whistling locomotive has the sound of a higher and higher 
pitch, and when receding the note descends in pitch. 



54 

Some substances have the property of appearing of different 
colors according to the angle at which they are looked at 
relatively to the source of light. They are, in part, tincture of 
night-shade or curcuma, extract of horse-chestnut, thin flakes of 
fuchsine, a solution of sulphate of quinine, aesculine, and canary 
glass (colored with compounds of uranium), a solution of chloro- 
phyl in alcohol, and a decoction of madder in alum. The effects 
are best seen with the help of a lens, which concentrates the 
rays upon the substance. 

Canary glass held in the light which comes into a dark room 
through blue cobalt glass is yellow ; because the high rate of 
vibration in blue rays is reduced by the yellow glass to that 
number of vibrations which produces yellow light. 

Polished silver exposed to iodine vapor acquires a flim of 
argentic iodide, which will turn black upon exposure to light. 
The black substance is insoluble in sodic hyposulphite, while 
argentic iodide is soluble. Mercury vapor is condensed upon 
the black surface, but not upon argentic iodide. The 
black substance is mostly pure silver in a very finely divided 
state. 

A photographic glass plate is glass which has been coated 
with collodion or gelatine containing potassic iodide and 
washed with an aqueous solution of argentic nitrate. 

*' Bromiodide emulsion" containing an aniline dye is not 
only the most sensitive to light, but is also highly sensitive to 
yellow light, so that yellow objects appear white in a positive 
photograph. With other ordinary photograph preparations the 
blackening in the negative is caused only by the violet and 
chemical rays, and not by yellow. 

A negative in the development of which ferrous sulphate is 
used instead of sodic hyposulphate, a bath of potassic cyanide 
turns to a positive. 

The eye of an animal is a camera. It is provided with a 
sensitive surface, which receives the image and connects with 
the brain by thousands of nerves. At the point where the 
nerves join the eye blindness exists, as may be proved by hold- 
ing a white card, having two small black spots, at reading dis- 
tance, the distance between the spots being equal to that between 
the eyes. Close the left eye and keep the other directed upon 
the left spot. The right spot is invisible because its image falls 
upon the spot where all the nerves join. The eye has its lens 
liquid for preventing the heat from injuring the eye; means 
for adjusting the focus according to the distance of 
the object viewed; and a variable opening for regulating 
the amount of light. 



55 

The image formed within the eye is inverted, as in a 
camera, but the brain, in some unknown manner, is so impressed 
that objects appear in their true position. 

A cannon ball during transit past the eyes is invisible. If 
itself luminous, a streak of light appears. If non-luminous, 
but illuminated by a flash, the ball appears as though it were 
stationary. Also, the spokes of a rapidly rotating wheel appear 
to stand still during a flash of lightning at night, whereas, in 
daylight the spokes are not separately visible. The above facts 
show that an impression remains upon the eye only when the 
eye views an object an appreciable length of time. A lighted 
candle viewed for a minute appears again when extinguished, 
and then disappears and reappears, and varies in color, becom- 
ing orange, then red, then violet, and greenish blue, showing 
that some colors remain upon the retina or sensitive surface of 
the eye longer than others. White light remains longest, then, 
in order, yellow, red and blue. 

White or bright objects against a black or dark background 
appear larger, and black against white, smaller than the real 
size. Illustration : A church steeple at a distance appears to 
lean over, due to unequal illumination of opposite sides. Ob- 
jects of one color, surrounded by a different color, are accom- 
panied in the eye by a fringe or edging of a color different 
from either. 

In the same sense that all the different vibrations due to an 
orchestra reach the ear without confusion, so do all the colors 
in a picture produce no confusion in the eye. The different 
colors give different rates of vibration to different nerves. 
Violet light corresponds to a high note and red light to a low 
pitch. The length of a vibration or swing of an atom in pro- 
ducing the red is .000027 in., and in the case of violet, .000015 i^- 

Lenses of gla^s produce single images in a camera. Lenses 
of certain crystals, as Iceland spar, produce double images. 
Glass, when annealed or compressed, has this property of double 
refraction. Such doubly refracting substances cause objects to 
appear double when looked through. Besides Iceland spar, the 
following, among other, substances have the property of double 
refraction : Tourmaline, sapphire, ruby, sodic nitrate, quartz and 
ice. 

Two rays of one color — /. e., having one set of vibration 
(white light having as many sets of different rapidity of vibration 
as there are colors) — may be made to interfere and annihilate 
each other by reflecting them from slight angular surfaces upon 
a wall. Alternate black and white lines are visible, whereas 
the black lines disappear if one ray is removed. If white light 



56 

is used, the black and bright lines are replaced bylines of differ- 
ent colors. 

Place a coin in a vessel. Look into the vessel over its 
edge so that the coin is just out of sight, and add water. 
The coin comes into sight. The reflected light in coming 
from the denser fluid, water, is bent in coming to the rarer 
fluid, air. 

Every object casts two shadows, a central or dark and a 
fringe or light shadow. 

In a camera an image exists, even if there is no surface to 
receive it. 

Pictures of a man running, each picture showing each suc- 
ceeding position of the limbs, head, feet, &c., brought rapidly 
before the eye and rapidly removed so that the eye sees one 
figuie at a time, and all the figures in rapid succession, make 
such an impression upon the eye as to form a single living pic- 
ture. The instrument for doing this generally is called a phena- 
kistoscope. When the different positions are taken by photo- 
graphy, it is called a kinetograph. They illustrate the principle 
that an image remains upon the retina of the eye an appreciable 
length of time. 

When air vibrates to produce sound, the particles move to and 
fro, as if in a cylinder in front of a reciprocating piston. The 
air is alternately compressed and rarefied. In the case of heat 
and light, a medium is supposed to exist in which the heat and 
light travel as vibrations, but the particles have motions in 
straight lines perpendicular to the direction in which the light 
is moving. They have the same motion as particles in a wave 
of water. The wave travels along horizontally, but the particles 
of water move up and down. The waves of a rope illustrate the 
vibrations of light and heat. The particles of a rope move 
transversely thereto. All facts uphold the above statements in 
regard to the nature of heat, but it is still theoretical. As 
to sound, no doubt exists as to its consisting of condensa- 
tions and rarefactions of a mass, whether solid, liquid, or 
gaseous. 

Chemical rays of light — /. e., those beyond the violet — may 
be stored by almost any substance. Illustration : Expose an en- 
graving or drawing or any print to sunlight. Take it to a dark 
room and press it upon photographic paper. The engraving 
will be photographed. The chemical rays absorbed by the 
paper produce the reactions in the same manner as the sun, 
only much more slowly. In printing photographs, the process 
continues in a dark room after exposure to light. After a few 
hours the effect is noticeable. 



57 
CHAPTER XII. 

Principles in Chemistry as Tools for Making Scientific 

Inventions. 



Every compound body, as, for instance, water, is composed 
of elements, the smallest particle of a compound being a mole- 
cule, and the smallest part of an element an atom. This prin- 
ciple is the foundation of chemistry. Iron, for example, is com- 
posed of atoms of the same kind; therefore iron is an element. 
No one has ever been able to find that it is a compound. No 
known chemical action discovers anything but iron. The small- 
est particle which exists is therefore composed of iron and is 
called an atom. Now let the iron be caused to rust. By this 
means the iron combines with the atoms of another element 
called oxygen. The smallest particle of the compound rust or 
iron oxide is a molecule. If this molecule is analyzed it is 
found composed of iron and oxygen. The number of elements 
is comparatively few, but compounds are numbered by the hun- 
dred. Some compounds are natural, but most have been made 
artificially, and there is no reason known why others cannot be 
made. At long intervals a new element is discovered, but 
knowledge of chemistry shows that if others are found they will 
probably be rare and practically useless. 

There are about sixty-three elements which may, as far as 
known, be composed of other elements. The composition of 
compounds may be known by analysis through the agency of 
burning them and studying the flame with a spectroscope, each 
substance giving its own peculiar visual signal. 

The solvent power of water is greater in scope and magni- 
tude than that of any other substance. 

Substances which are merely mixed together are not com- 
pounds, and may be separated therefrom by mechanical filtra- 
tion, by evaporation or distillation, or by hand. 

Elements of a compound which have a stronger attraction 
for other elements than for each other will leave the former and 
unite with the latter, as illustrated by zinc in contact with sul- 
phuric acid — it takes the oxygen and sulphur from the sulphuric 
acid and liberates the hydrogen. 

Whenever two or more elements combine to form a com- 
pound the said compound differs from either element in one or 
all of the following respects : Conductivity of heat, sound and 
electricity, hardness, weight, color, and more or less in other 
physical properties. 



58 

The composition of bodies is generally made known by re- 
acting upon them with other known compounds or elements. 
Thus, common salt looks like a thousand other substances and 
tastes like other compounds, and its other physical properties 
are much like those of other compounds. How shall its com- 
position be known ? React upon it with sulphuric acid and 
manganic oxide under the influence of heat. A green gas issues 
which will bleach vegetable colors. This gas, chlorine, could 
not have come from the sulphuric acid nor the manganic acid, 
therefore it must have come from the common salt ; by reactions 
of other chemicals it is found that the common salt contains 
sodium. By means of chemical reactions compounds may be 
made as well as analyzed. If sodium is introduced into the 
green gas and heated, a bright fire is caused, resulting in a white 
smoke, which is found to be common salt, chemically called 
sodic chloride. 

Compounds may also be analyzed by the electric current. 
If the terminals of a circuit are placed in an aqueous solution 
of cupric sulphate pure copper is separated from the sulphate 
and deposited upon one of the terminals. Scarcely a compound 
exists which is not decomposed by the passage of an electric 
current through its aqueous, acid or alkaline solution. Com- 
pounds may also be formed by the electric current. Thus, if the 
current in the above is closed upon itself the deposited copper 
on the terminal unites with one or more of the elements of the 
electrolyte and forms a compound therewith. A current passed 
from one lead terminal to another of the same substance in an 
electrolyte of sulphuric acid causes the compound known as 
plumbic peroxide to be formed upon one of the lead terminals. 
If the source of current be removed and the terminals closed 
upon themselves, the plumbic peroxide becomes analyzed to 
such an extent as to be reduced to a lower oxide, which is a 
new compound, differing widely m chemical and physical prop- 
erties from the peroxide. 

An electric current will, therefore, sometimes analyze com- 
pounds and sometimes combine elements into compounds. This 
is also true of heat and light. 

Chemicals often combine or separate by reactions upon one 
another at the ordinary temperature. 

It is by chemical actions that life is supported. Hold a glass 
tube in the mouth and breathe through the same while the other 
end dips in clear lime-water. Soon the water becomes milky, 
due to the formation of carbonate of lime. The oxygen which 
enters the lungs combines with carbon of the body, forming car- 
bonic acid gas, which when exhaled unites with the lime and 



59 

forms carbonate of lime. In a perfectly closed room, lo feet 
on each side, death would ensue in a very few hours because the 
oxygen would be used up. The life-giving oxygen would be 
turned into the poisonous carbonic acid. 

Vegetable life is supported by chemical action. Grains con- 
tain phosphorus ; therefore fertilizers for grains should contain 
phosphates. Ammonia occurs in manures, and it is from that gas 
that plants obtain their nitrogen. The leaves are the nostrils of 
the plants, whereby the carbonic acid of the atmosphere is inlialed 
so that the plants may possess carbon, which may subsequently 
be obtained by means of a kiln. 

Metals, generally, are reduced from their ores by chemical 
reactions. The ores are mixed with those substances with which 
the non-metallic elements of the ores have stronger attraction 
than the metals. Those ores, which are oxides, may be mixed 
with carbon and heated to a high temperature. The oxygen 
leaves the metal and joins the carbon, forming carbonic acid, 
which escapes into the atmosphere, leaving the metal free. Car- 
bonate ores are mixed with lime. The carbonic acid leaves the 
metal under high heat in presence of the lime and goes to the 
lime, forming carbonate of lime. 

The metals which will decompose water without applying 
heat are calcium, strontium, barium, sodium and potassium — 
the same uniting with oxygen of the water and liberating hydro- 
gen. The products formed are the oxides of the metals. Any 
metals decompose water if they form the terminal of an electric 
circuit and are dipped into the water. Decomposition is has- 
tened by adding an acid to the water. Very intense heat will 
decompose steam. If iron or other easily oxidizable metal is in 
contact with the steam, the oxide of that metal is formed. 

One of the most important characteristic differences between 
physical and chemical changes is that whereas in a chemical 
change the bodies subjected to the change have different chem- 
ical and physical properties after the change ; while before and 
after a physical change the bodies have the same physical and 
chemical properties except, sometimes, as to degree. Illustra- 
tration : Chemically change iron by burning it until it is iron 
rust — /. e.y ferric oxide. Although the iron is still in the ferric 
oxide, yet the oxide has none of the characteristics of iron nor 
of oxygen ; for example, iron is magnetic, its rust is non-mag- 
netic ; iron has a metallic lustre, its oxide has none. Iron is 
nearly eight times as heavy as water, while its oxide is only 
slightly heavier. Iron has a different color from its oxide. But 
suppose a physical change is produced in iron, it still remains 
iron. Suppose it undergoes the physical change of being 



60 

melted, It is still iron, and has the important chemical and phy- 
sical properties of iron. Chemical changes are thus distinguish- 
able from physical changes. 

Elements differ from compounds in being non-decomposable, 
and compounds from mixtures as having different chemical and 
physical properties from the elements of which it is made, while 
a mixture is made of elements or compounds which have no 
chemical union but still possess the properties of its con- 
stituents. 

The metallic elements are aluminium, Al II ; antimony, Sb 
III ; arsenic, As III; barium, Ba II; bismuth, Bi III; cadmium, 
Ca II; caesium, Cs I; calcium, Ca II; cerium, Ce II; chromium, 
Cr II; cobalt, Co II; copper, Cu II; didymium, D II; erbium, 
E; glucinum, Gl; gold, Au III; indium, In II; uridium, Ir IV; 
iron, Fe II; lanthanum. La II; lead, Pb II; lithium, Li I; mag- 
nesium, Mg II; manganese, Mn II; mercury, Hg II; molyb- 
denum, Mo VI; nickel, Ni II; niobium, Nb V; osmium, Os IV; 
palladium, Pd II; platinum, Pt II; potassium, K I; rhodium, 
Rh II; rubidium, Rb I; ruthenium, Ru I; silver, Ag I; sodium, 
Nal; strontium, Sr II; tantalum, TaV; thallium, Til; thorium, 
Th IV; tin, Sn IV; titanium, Ti IV; tungsten, W VI; uranium, 
U III; vanadium, V III; yttrium, Y II; zinc, Zn II; zirconium, 
Zr IV. 

The non-metallic elements are boron, B III; bromine, Br 
I; carbon, C IV; chlorme, CI I; fluorine, F I; hydrogen, H I; 
iodine, I I; nitrogen, N III; oxygen O II; phosphorus, P III; 
selenium, Se II; silicon. Si IV; sulphur, S II; tellurium, Te II. 

The meaning of the numerals and abbreviations is given 
later. 

The general distinguishing characteristics of metals are their 
fusibility, hardness, ductility, comparatively heavy weight. They 
can be welded, they have an appearance always recognizable, 
and are good conductors of heat and electricity. 

The composition of well-known alloys are explained thus : 
Copper and zinc make brass ; lead and tin, solder and pewter ; 
copper and tin, gun speculum and bell metal; twenty-two parts 
of gold to two parts of copper, standard gold; mercury and 
another metal, amalgam ; bismuth and another metal, fusible 
metal; bismuth, five parts; tin, two parts; lead, three parts, an 
alloy fusible in boiling water; antimony and lead, type metal. 
Zinc, tin, lead and cadmium impart to their own alloys their 
own peculiar properties in proportion to the amounts contained 
in the alloys. Other metals do not impart their properties to 
their alloys in the proportion in which they exist in the alloys. 
The specific gravity and coefficient of expansion of the alloys 



61 

containing two or more of the metals lead, tin, zinc and cadmium 
are the average of those of the metals forming the alloy. Other 
properties, as, for example, the fusing point, vary from those of 
the constituents of the alloy. The fusing points of tin, bismuth, 
cadmium and lead are respectively 235°, 270°, 315° and 334° C, 
while their alloy fuses at 65°. It is a peculiar coincidence that 
mixtures of certain salts melt at a lower temperature than the 
average of its constituents. Illustration : Potassic and sodic 
carbonates when mixed fuse at a much lower temperature than 
either would alone. The same is true of the chlorides of those 
metals. The alloys of the said metals, lead, tin, zinc and cad- 
mium, with each other have electric and heat-conducting powers, 
which are directly proportional to the proportions in which they 
exist, but this is not true of the alloys of the other metals. 
Copper is soft, but with the addition of a little zinc it becomes 
hard. Sometimes an alloy is soluble in an acid, while one of its 
constituents is not. This is the case with an alloy of silver and 
platinum, which is soluble in boiling nitric acid, while platinum 
by itself is not acted upon at all. On the other hand, an alloy 
of gold and silver is not soluble in nitric acid, but silver by itself 
is soluble. 

The combination of the elements with one another and in 
different proportions form hundreds of compounds. 

An example of a mixture is that of wax and sand. Each 
retains its own properties. By mixing different elements or 
compounds together the result is a mixture or compound accord- 
ing to whether a substance has been formed which has different 
properties from any of its constituents. 

Liquids and gases will gradually mix together, even if 
separated by a porous membrane, and a peculiar action 
is that the denser will pass through as much slower as it 
is denser. 

Chemicals unite to form compounds because there exists a 
force of attraction among the elements. This attraction differs 
from cohesion or adhesion in that it does not exist between the 
atoms of the same element nor between the molecules of the 
same compound. Thus, a piece of lead has cohesion among its 
atoms, holding them together. It has also adhesion because 
another piece of lead is held by it, but it has no chemical attrac- 
tion for its own atoms. Chemical attraction exists only between 
atoms or molecules of different kinds of substances. Thus, in 
paper, oxygen, hydrogen and carbon are so strongly and inti- 
mately held together that howsoever finely the paper may be 
subdivided by a knife or other mechanical means these elements 
do not separate. 



The less the cohesion the greater the effects of chemical 
attraction. Thus, in liquids the cohesion is least and molecular 
repulsion is least, and in the liquid condition compounds gene- 
rally are most easily formed, as illustrated by solid calcic chlor- 
ide and amnionic fluoride, which do not combine in the solid 
state, but they do if first dissolved in water. A powder sepa- 
rates from the water and is found to be calcic fluoride. The 
fluoride leaves the ammonia and combines with the calcium. 

The chemical attraction is sometimes so strong that solids 
combine directly, being so powerful that the atoms of either 
body overcome the cohesion in the other body. I'hus, sal 
ammoniac (ammonic chloride) and lime are both solid and have 
no odor. Let them be mixed together, immediately the smell 
of ammonia is very strong. The atoms of the lime unite with 
some of those of the chloride, liberating the ammonia gas, which 
gives the odor. Agam, a bright fire is obtained by simply 
touching together solid iodine and solid phosphorus. The 
smoke consists of phosphoric iodide. The atoms of the phos- 
phorus and iodine separate from each other in each solid and 
come together again in such a manner that each atom of phos- 
phorus takes three atoms of iodine, making one molecule of 
phosphoric iodide. 

It is a curious principle that if substances are soluble in 
water or acids they will combine if the compounds are such as 
to be insoluble in the liquid. Dissolve aluminic sulphate in 
water. Add a solution of ammonia in water. A white powder 
is formed, which does not dissolve, and which is found to be a 
new compound, consisting of aluminic oxide, which is called a 
precipitate, because it falls to the bottom of the vessel. 

Sometimes two solutions of two compounds when mixed 
result in two insoluble compounds, with nothing remaining in 
solution. Mix together solutions of argentic sulphate and 
baric chloride. The precipitates are baric sulphate and argentic 
chloride. When filtered, the solution contains nothing, unless 
an excess of one compound exists. Any given free element 
unites with one or more free elements at fixed temperatures, 
differing according to the particular elements. 

Illustration : Hydrogen and oxygen unite at about the tem- 
perature of 1, 000° F. in the case where each is isolated from 
other elements. Above that temperature they will not unite. 
The heat causes the repulsion between the atoms to be stronger 
than the chemical attraction. Below that temperature they will 
not separate, because the chemical attraction is greater than the 
repulsion due to heat. About the only exception is that of 
chlorine and hydrogen, which have two temperatures or kind- 



63 

ling points. In the dark a very high temperature is required to 
cause them to unite, while in diffused daylight they are kindled 
at approximately the ordinary atmospheric temperature. There 
is no reason to believe that the same amount of work is not 
done ; for with a high temperature the union is instantaneous, 
while with diffused daylight (not in the sun) a long time is con- 
sumed — the action is slow but long. If the oxygen and hydro- 
gen are associated with other compounds, they often unite at 
approximately the ordinary temperature. Thus in the decay of 
wood, oxygen and hydrogen leave the carbon and form water. 
Again, when sulphuric acid acts upon sugar, the hydrogen and 
oxygen leave the sugar at about 120° F. in the proportion to 
form water and unite with the sulphuric acid, which becomes 
more dilute. The principles are, therefore : {a) That isolated 
elements unite at a fixed temperature, which depends upon what 
the elements are. The temperatures vary all the way from the 
ordinary temperature to many hundred degrees. (^) Elements 
already combined leave one ar other to join foreign elements 
alone or compound at a lower temperature than that at which 
they would combine if isolated. How many hufidreds of com- 
pounds are formed by this principle! 

Howsoever finely substances are mechanically pulverized, 
chemical action is not generally facilitated, as it is when 
the substances are dissolved. An exception is that of 
sulphur and potassic chlorate. Pulverize them finely and 
mix intimately. Suddenly they combine with a dangerous 
explosion. 

Hydrogen and oxygen always combine in fixed proportions 
by volume to form water. One gallon of oxygen combines with 
two gallons of hydrogen. With different proportions, a residue 
of one of the gases is found. Hydrogen and chlorine combine 
in the proportion of one volume of each to form hydric chloride. 
Any given compound is always and only formed by the com- 
bination of the elements in a fixed proportion. However, ele- 
ments often combine in different proportions, but the com- 
pounds are different. Thus nitrogen and oxygen combine in 
five different proportions by volume. One volume of hydrogen 
can unite with one or two or three, etc., volumes of many other 
elements and compounds. 

What is true of combining volumes is true of combining 
weights; elements or compounds combine in different propor- 
tions by weight ; but the same proportional weights always pro- 
duce the same compound. A few important exceptions exist. 
Starch and dextrine have equal weights of each of its elements. 
Each has 6 parts of carbon, 10 of hydrogen and 5 of oxygen. 



64 

Although having exactly the same chemical composition, starch 
and dextrine have different physical properties. 

A few exceptions exist also as to atoms of the same sub- 
stance combining with each other. One atom of oxygen can be 
made to combine with another atom of oxygen, whereby ozone 
is formed. The difference between the element and its 
compound is that whatever property oxygen has, ozone has the 
same magnified. Thus oxygen bleaches very slowly ; ozone 
bleaches rapidly. 

Elements which are free may combine to form compounds. 
It is also true that the elements of one compound will often 
depart and combine with the elements of another compound, or 
with other free elements. Potassium will combine with free 
oxygen, or it will take oxygen from water. In both cases 
potassic oxide is formed. 

How is it known that a chemical change occurs ? By change 
of color, of form, of temperature or production of electricity. 
Gunpowder when exploded changes from the solid to the gaseous 
form. Sulphuric acid added to copper produces a blue sub- 
stance — cupric sulphate Silver and copper placed on the 
tongue and brought in contact with the terminals of a delicate 
galvanometer are found to deflect the needle. Sulphuric acid 
added to syrup produces heat. In all these cases new com- 
pounds are formed. 

Compounds which at the same time are sour to the taste, 
which turn blue litmus paper red, which are composed of non- 
metals, and which contain hydrogen, are acids ; those acids 
which contain- hydrogen only are called hydracids. Those 
which contain hydrogen and oxygen are oxacids. An acid is in 
nearly every case a combination of either oxygen and hydrogen 
or hydrogen alone with a non-metal. When an acid is named, 
therefore, the above rule enables one to name its constituents. 
Thus, bromic acid contains oxygen, hydrogen and bromine. 
Hydro fluoric acid contains hydrogen and fluorine. 

Non-acids, called hydrates, and formerly called alkalis, have 
opposite properties from those of acids, since they turn red 
litmus paper blue; have a caustic taste; and are composed of 
hydrogen, oxygen and a 7?ietal^ while acids do not contain a metal. 

Hydrates are named in such a manner that their composi- 
tions are apparent Thus, baric hydrate is the combination of 
hydrogen and oxygen with the metal barium; ferric hydrate has 
hydrogen, oxygen and iron, and calcic hydrate has hydrogen, 
oxygen and calcium. 

There are two hydrates of iron, the ferr/V and the f err^z/^, the 
latter containing less oxygen, and so with some other metals. 



65 

Instead of speaking of silver hydrate, iron hydrate, &c., the 
Latin words are used for the sake of euphony and system, but in 
many the English is adhered to, as in cobaltic hydrate, meaning 
that hydrate which contains cobalt. 

If calcic hydrate is heated, all the hydrogen and enough 
oxygen escape to form water (/. e., one part of oxygen to every 
two of hydrogen.) The remainder is calcic oxide. So with 
other hydrates. They may be reduced similarly to oxides, not 
necessarily by heat; but that product which is left by removing 
all the hydrogen and enough oxygen to form water is the oxide 
of the metal. The oxides are so named that their constituents 
are apparent. Thus, chromic oxide is composed of the metal 
chromium and oxygen. Auric oxide has gold and oxygen. 
Zincic oxide has zinc and oxygen. When two oxides of the 
same metal occur, the suffixes ic and ous are used as before, but 
sometimes there are three oxides of the same metal. Recourse 
is then had to the prefixes mon, meaning one part of oxygen; di^ 
meaning two parts, and /r/, meaning three parts. Chromic 
trioxide has three parts of oxygen, while chromic monoxide has 
one part. 

Metallic oxides need not always be made by removing hy- 
drogen and some of the oxygen from hydrates. Thus, potassic 
oxide may be formed by burning potassium in dry air, but the 
result as far as the proportions of the elements in the oxide are 
concerned is the same as if formed from hydrates in the man- 
ner set forth. 

Acids turn blue litmus paper red. Hydrates turn red litmus 
blue. There is a third class of compounds which will neither 
turn red litmus blue, nor blue litmus red, nor will it have any 
coloring effect upon litmus; neither does it have any acid or 
burning taste. They are called neutral compounds. The com- 
bination of a metal with a non-metal forms a neutral compound. 
The name distinguishes the constitutents. Thus, manganic 
chloride has manganese and chlorine. Ide is the suffix. Ide is 
used to indicate a neutral binary compound. 

Exceptions: Some oxides of non-metals are neutral. 
Example: Water, carbonic oxide, nitric oxide, and a very few 
others. 

The hydrogen in an acid may be replaced in part or wholly 
by a metal. Thus, in sulphuric acid (an oxacid) the hydrogen 
can be replaced by zinc, whereby the compound is changed to 
zincic sulphate. The name given to a compound thus obtained 
is called a salt. Common salt (sodic chloride) may be formed 
by adding sodium to the hydracid, called hydric chloride. The 
sodium expels the hydrogen and unites with the chlorine. Where 



6G 

the oxacid is used the word ends in afe or t^e, according as to 
whether there is more or less oxygen. If made from a hydracid, 
the word ends in ide, as in the formation of the names of neutral 
binary compounds. Examples of the formation of salts: Silver 
added to the oxacid nitric acid results in argentic nitrate; iron 
added to the oxacid sulphuric acid forms ferric sulphate. Lead 
added to the hydracid, hydric chloride, forms plumbic 
chloride. 

Some substances in chemistry have unsystematic names and 
greatly hinder the growth of the science, as system and regu- 
larity are prevented. Some are named after men, as Glauber 
salts. The proper name is sodic sulphate, which by its very 
name shows its own composition. Oil of vitriol is sulphuric 
acid. Saltpeter is potassic nitrate. Soda is sodic oxide. Pot- 
ash is potassic hydrate. Sulphuretted hydrogen is hydric 
sulphide. 

Oxacids, hydracids, anhydrides, hydrates, neutral binary 
compounds, and salts are indicated not only as to their com- 
position by their names, but also by symbols containing figures 
which indicate the propotional amounts of the elements in the 
compound. For the sake of brevity, initials of the names of the 
elements are employed. Sometimes the initial of the Latin 
word is used, so that the same letter for different elements may 
be avoided. Thus, H2SO4 is an oxacid, called sulphuric acid. 
The figures 2 and 4 show that there are two parts by weight and 
volume of hydrogen and four of oxygen. S has no number, but 
one part of sulphur is understood. These symbols are very use- 
ful in showing the reactioms between compounds. Thus Zn + 
H2SO4 = H2 + ZnS04. 

The metal zinc replaces hydrogen in the oxacid and changes 
it to the salt, zincic sulphate. To show the composition of 
water, the equation is thus : 

H2 + O = H2O. 

To show how an oxacid is turned into an anhydride, this 
equation is an example: 

H2SO4 — H20 = SO3 (sulphuric anhydride.) 

The following equation shows how a hydrate is changed to a 
metallic oxide: 

2KHO (Potassic hydrate) — H2O = K2O. 

Some elementary atoms have the power of combining with i 
atom of hydrogen, some with 2, some with 3, and some with 4, 
5 or 6. Illustration: In HCl (hydric chloride) i atom of 
chlorine is combined with i of hydrogen. In H2O (water,) i 
atom of oxygen is combined with 2 of hydrogen. In H3, N 
(immonia) i atom of nitrogen is combined with 3 of hydrogen. 



67 

In H4C (marsh gas) i atom of carbon is combined with 4 of 
hydrogen. 

That elementary substance whose i atom combines with i of 
hydrogen is termed a monad, from the Greek for unity. Sim- 
ilarly those which take up 2, 3, 4 atoms of hydrogen are called 
dyads, triads and tetrads respectively. 

It is a principle that i atom of a monad will combine with 
I atom of another monad; that 2 atoms of a monad will com- 
bine with I atom of a dyad, or 2 atoms of another monad; that 

3 atoms of a monad will combine with i atom of a triad, or with 
I atom of a dyad and i of a monad, or with 3 atoms of a monad, 
and so on in the arithemtical manner. So also with dyads. One 
atom takes 2 monads, or t dyad. Two atoms of a dyad take 4 of a 
monad, or i monad and i triad, &c. In this manner it is only 
necessary to know whether an atom is a monad, dyad, triad, &c., 
in order to know the proportional amounts of elements in any 
given compound whose elements are known, and to be able to 
write the symbols of compounds and to foreknow the new com- 
pounds which will be formed in any chemical changes. 

The monad, dyad, triad, &c., elements are indicated by the 
Roman numerals found after the names of the elements hereto- 
fore given. 

A dyad may replace 2 monads, a triad, 3 monads, or i 
monad and i dyad, &c. Thus, in H2O the dyad oxygen may 
be replaced by 2 atoms of the monad chlorine, making the com- 
pound which is equal to 2H CI. — /. ^., two molecules of hydric 
chloride. CH4 is one of the important constituents of coal 
gas. The tetrad C (carbon) may unite with 2 atoms of the dyad 
oxygen, which will replace 4 atoms of the monad hydrogen. The 

4 atoms of the monad hydrogen will also unite with 2 atoms of 
the dyad oxygen, forming water. The following equation shows 
the reactions, assuming that the supply of oxygen is plentiful: 

CH4+ 04=C02 + 2 H2O. 

This is just what happens when marsh gas (CH4) is burned 
in air. Carbonic di-oxide, CO2, and water, H2O, are formed. 
Similarly any reactions can be predicted. Suppose that zinc is 
added to hydric chloride. Zinc is a dyad, therefore the equa- 
tion is: 

Zn + 2 HCl = Zn CI2 + H2. 

It is known that there should be 2 molecules of H CI, because 
Zn must have 2 atoms of the monad CI in order to be satisfied. 

Sometimes compounds exist which are not " satisfied " ; but 
they are unstable; they become satisfied when opportunity 
offers. Thus, if carbon is burned in a limited supply of oxygen 
the lower oxide, CO, is formed. Since C is a tetrad and O is a 



68 

dyad, the compound is not satisfied. The carbon can take up 
another atom of oxygen, and experiment shows that it does so 
when the CO is burned in air, whereby carbon di-oxide, CO2, 
is formed. CO is one of the constituents of coal gas, being 
combustible, while CO2 is one of the gases escaping from a gas 
flame. 

Some reactions are given below employing the above prin- 
ciples. 

Na (Sodium, monad) + H2O = H Na O + H. 

The above is the reaction when metallic sodium is placed 
upon water. The products are sodic hydrate and hydrogen. 

Fe (iron) + H2S O4 = Fe S O4 + 2H. 

In the above, the dyad Fe takes the place of 2 atoms of the 
monad H in the compound H2SO4. 

Ca CO3 (calcic carbonate) + Na2S (sodic sulphide). = 

Na 2 CO3 (sodic " ) + Ca S (calcic " ). 

Two atoms of the monad sodium change places with i atom 
of the dyad Ca. 

The following compounds of metals are more or less soluble 
in water : 

Acetates, except that of calcium; chlorates; chlorides, except 
those of mercurosum and silver; formates; iodides, except that 
of silver; nitrates; sulphates, except those of antimony, barium 
lead and strontium; fluoride, except those of barium, calcium, 
copper, lead, magnesium, manganese and strontium; benzoate, 
except those of copper, tetrad, iron, lead, mercurosum; bromide, 
except those of mercurosum and silver; citrate, except those of 
barium, cadmium, lead, manganese, mercurosum, silver and 
strontium; ferrocyanide, except those of cobalt, dyad, iron, man- 
ganese, nickel, silver and zinc; malate, except that of mercu- 
rosum; succinate, except those of lead, mercurosum, silver and 
tetrad tin; tartrate, except those of antimony, barium, bismuth, 
calcium, lead, mercuricum, nickel, silver, strontium, dyad, tin 
and zinc; arseniate of ammonium, of potassium and sodium; 
arsenite of ammonium, of potassium and of sodium; borate of 
ammonium, of cadmium, of magnesium, of potassium and of 
sodium; carbonate of ammonium, of potassium and of sodium; 
chromate of ammonium, of calcium, of copper, of tetrad iron, 
of magnesium, of mercuricum, of nickel, of potassium, of sodium 
and of zinc; cyanide of ammonium, of barium, of calcium, of 
magnesium, of mercuricum, of potassium, of sodium, of strontium; 
ferrocyanide of ammonium, of barium, of calcium, of magnesium, 
of potassium, of sodium and of strontium; hydroxide of am- 
monium, of barium, of calcium, of potassium, of sodium and of 
strontium; oxalate of ammonium, of chromium, of manganese 



69 

of potassium, of sodium and of tetrad tin; oxide of barium, of 
calcium, of potassium, of sodium and of strontium; phosphate 
of ammonium, of antimony, of barium, of calcium, of potassium, 
of sodium; silicate of potassium and of sodium; sulphite of 
ammonium, of barium, of calcium, of potassium, of sodium and 
of strontium; aluminium ammonium sulphate; aluminium po- 
tassium sulphate ; ammonium arsenic chloride ; ammonium 
sodium phosphate ; ammonium ferrous sulphate ; ammonium 
cupric sulphate; ammonium potassium tartrate; antimony po- 
sassium tartrate; chromic potassium sulphate; iron (ferric) po- 
tassium tartrate; platinic bromide, chloride and cyanide, nitrate, 
oxalate and sulphate. 

The following compounds of metals are more or less soluble 
in one or more of the acids, nitric (HNO3), sulphuric (H2SO4), 
and hydrochloric (H CI) : 

Arzeniates, except those of ammonium, potassium and so- 
dium; arsenites, except those of ammonium, potassium and 
sodium; borates, except those of ammonium, potassium and 
sodium; carbonates, except those of potassium and sodium; 
chromates, except those of ammonium, copper, tetrad iron, 
magnesium, nickel, potassium and sodium; cyanides, except 
those of ammonium, calcium, magnesium, mercuricum, potas- 
sium, sodium and strontium; hydroxides, except those of am- 
monium, barium, potassium, sodium and strontium; oxalates, 
except those of ammonium, potassium, sodium and tetrad tin; 
oxides, except those of barium, potassium, sodium and strontium; 
silicates, except those of potassium and sodium ; sulphides, 
except those of ammonium, barium, potassium, sodium and 
strontium; tartrates, except those of aluminium, ammonium, 
chromium, cobalt, copper, tetrad iron, potassium and sodium; 
phosphates, except those of ammonium, potassium, sodium ; 
acetate of calcium and of mercurosum; benzoates of copper, 
tetrad iron, lead, of mercurosum, mercuricum, silver; bromides 
antimony, bismuth, mercurosum, silver; chlorides of antimony, 
bismuth, mercurosum ; citrates of barium, cadmium, calcium, 
lead, manganese, mercurosum, mercuricum, silver, strontium, 
zinc; cyanides of barium, cadmium, chromium, cobalt, copper, 
dyad iron, lead, manganese, nickel, zinc; ferrocyanides of lead, 
zinc; ferrocyanides of barium, lead, manganese, and of zinc; 
fluorides of barium, cadmium, cobalt, copper, dyad iron, lead, 
magnesium, manganese, mercuricum, nickel, strontium, and of 
zinc; formates of lead; iodides of antimony, bismuth, lead, 
mercurosum, mercuricum; malates of barium, calcium, lead, 
mercurosum, mercuricum, and silver; succinates of aluminium, 
barium, calcium, cobalt, of copper, of lead, of mercurosum, of 



70 

silver, of strontium, tetrad tin, and zinc; ammonium magnesium 
phosphate; antimony oxychloride; bismuth oxychloride; bismuth 
basic nitrate ; calcic sulphantimonate ; mercurius solubilis 
Hahnemanni; mercurammonium chloride; mercuric sulphate, 
basic; potassium platinic chloride. 

The following compunds of metals are among those which 
are insoluble in the acids above named: 

Chloride of silver; cyanide of silver; ferricyanide of cobalt, 
of dyad iron, of manganese, of nickel and of silver; ferrocyanide 
of cobalt, of copper, of dyad iron, of tetrad iron, of nickel, of 
silver; iodide of silver; sulphate of strontium. 

It is a very peculiar phase of combination that certain atoms 
of different elements change place from one compound to 
another and have a fixed proportion for combining. The prin- 
cipal compounds of this class are stated thus, with the proper 
word, monad, dyad, &c., to indicate their power of combining 
with other monads, dyads, &c.: 

NH4, monad, is a root of ammonia compounds. Example: 
(NH4) CI (ammonic chloride). 

NO3, monad, is a root of nitrates. Example: Ca (N03)2 (calcic 
nitrate). 

CO3, dyad, is a root of carbonates. Example: Ba {CO3). 

SO4, dyad, is a root of sulphates. Example: Cu SO4 (cupric 
sulphate). 

HO, monad, is a root of hydrates. Example: KHO (potassic 
hydrate). 

CN, monad, forms the root of cyanides. 

PO4, a triad, forms the root of phosphates. Example: Hg3 
(P04)2 (mercuric phosphate). 

Any one of these roots will go from one compound to another 
in certain reactions without themselves appearing to undergo 
any decomposition. Example: Cu4- H2(S04) — H2 + Cu (SO4). 

The operation is that when copper is dissolved in sulphuric 
acid (H2SO4), the root (SO4) goes from the zinc to the copper 
and the hydrogen is set free. It is another wonderful freak, 
that these roots never exist by themselves, unless that infinitesi- 



71 

mal time taken in passing from one compound to another be 
considered ; but by losing or gaining another atom of one of the 
elements, they exist alone. Example: 

Taking H from NH4 leaves NH3 (ammonia). 

" O " SO4 " SO3 (sulphurous acid). 

" O " CO3 " CO2 (carbonic di-oxide). 

Adding H to HO gives H2O (water). 

The gist of practical chemistry is that relating to an accurate 
and extended knowledge of the reactions which occur among 
chemical compounds. One should follow the equations below, 
taking notice of the exact composition of each chemical, and 
how the foregoing principles have been applied. In order to 
make the equations easily intelligible, the name of the com- 
pound often accompanies the symbol. The compounds on the 
left undergo an exchange of some of their elements, and two or 
more new compounds are formed, according to the rules already 
stated. One of the new compounds is generally a precipitate 
— /. e., one of the new compounds is insoluble and falls as a 
powder to the bottom of the vessel and may be obtained free 
by filtration. An assistance in this respect will be the list of 
soluble and insoluble compounds already given. Sometimes the 
new compound or liberated element is a gas and escapes into 
the air or into a vessel provided for the purpose. Sometimes 
heat is necessary in order to make the reaction take place. 
Sometimes both compounds remain in solution. The equations 
are as follows : 

Cu (copper) + O = Cu O (cupric oxide). 

0+02 = CO2 (carbonic di-oxide). 

Cu + H2 SO4 (sulphuric acid) == Cu O4 (cupric sulphate) + 2H. 

Zn + H2 SO4 = Zn SO4 (zinc sulphate) + 2H. 

Fe + H2 SO4 = Fe SO4 (ferric sulphate) -f- 2H. 

2 Na (sodium) + 2 (H2O) = 2(Na HO) (sodic hydrate) + 2H. 



72 

2 K (potassium) + 2(H20) = 2(KH0) + 2H. 

Fe3 + 4 H2O = Fes O4 (ferric oxide) + 8H. 

Cu O (cupric oxide) -|- 2H = Cu + H2O. 

NaaO (sodic oxide) + H2O = 2(Na HO) (sodic hydrate). 

Ca O (calcic oxide) + H2O (water) = Ca (H0)2 (calcic 
hydrate). 

P2OS + 3 (H2O) = 2(H3 PO4). 

2 (HCl) (hydrochloric acid) + Ba H2 O3 (baric hydrate) = Ba 
CI2 (baric chloride) + H2 O2 (peroxide of water) -\- 
H2O (water). 

Ag2 SO4 (argentic sulphate) + Ba CI2 = 2 Ag CI (argentic 
cloride) -\- Ba SO4 (baric sulphate). 

Ba CI2 (baric chloride) + H2 SO4 (sulphuric acid) + Ba SO4 
(baric sulphate) + 2 (HCl) (hydrochloric acid), 

H2 O + Cl2 = Cl HO (chloric acid) + HCl (hydrochloric acid) 
NH4 (NO2) (ammonia nitrate + slight heat = N2 + 
2 H2O). 

KNO2 (potassic nitrite) + NH4 CI (ammonic chloride) + H2O 
= KC1 + NO2 NH4 (ammonic nitrate) + H2O. 

H2 804+ KNO3 = HKSO4 (double sulphate of potassium and 
hydrogen) + HNO3 (hydric nitrate, commonly called nitric 
acid). 

Cu3 + 8(HN03 = 3(Cu (N03)2) (cupric nitrate) + 2 (NO) 
(nitric oxide). 

HNO3 + KHO = KNO3 + H2O. 

Pb (N03)2 (plumbic nitrate) + heat = PbO (plumbic oxide) + 
N2O4 (nitric peroxide) + O. 

NO (nitric oxide) + 5H + heat = NH3 (ammonia) + H2O. 



is 

H2 SO4 (hydric sulphate, called also sulphuric acid) + 2KNO3 
= K2 SO4+ 2HNOS, 

2 (NH4 CI) (ammonic chloride) + Ca H2O (calcic hydrate) 
= 2NH3 + Ca CI2 + 2 (H2O). 

(NH4) HO (ammonic hydrate) + HNO3 = (NH4) NO3 + H2O. 

HNO3 + KHO = KNO3 + H2O. 

Pb (N03)2 + 2 (NH4)H0) = 2( (NH4)N03) (ammonic 
nitrate) + Pb (HO) 2. 

HNa CO3 (double carbonate of sodium and hydrogen) + 
H2SO4 = H Na SO4 + H2O + CO2. 

CH4 (carburetted hydrogen or carbonic hydride) + 2O2 + heat 
= CO2 + 2H2O. 

Mn O2 (manganic oxide) + 4(HC1) + heat = Mn CI2 + CI2 + 
2 H2O. 

CI2 + 2(KH0) = KCl + KCl O + H2O. 

Ba (CI 03)2 (baric chlorate) + H2SO4 = 2(HC1 O3) (hydric 

chlorate) -}- Ba SO4. 

Cl2 + H20 + AgN03 (argentic nitrate) = Ag CI + HCl O + 
HNO3. 

HCl + HCl O = CI2 + H2O. 

H2SO4 -f- Na CI = Na HSO4 + HCl. 

Na HSO4 + Na CI = Na2S04 + HCl. 

KHO + HCl = KCl + H2O. 

Hg2 (N03)2 + 3(HC1) = 2Hg CI (mercuric chloride) + 
2(HN03). 

(NH4)2 CO3 + Ca a2 = 2(NH4 CI) + Ca CO3. 



CA SO4 + Ba 2(N03) = Ca 2 (NO3) + Ba SO4. 

2 (Ag NO3) + Ca CI2 = 2 (Ag CI) (argentic chloride) + Ca 
(N03)2. 

Pb (N03)2 + H2 S (hydric sulphide) = 2 (HNO3) + Pb S. 

2 (HNO3) + Ba H2O = Ba (N03)2 + 2 (H2O). 

2 (As CI3) (arsenic chloride) + 3 (H2S) - 6 HCl + As2 S3 
(arsenic sulphide). 

Bi CI3 (bismuth chloride) -f- ^ KI (potassic iodide) = Bi I3 + 
3 (KCl). 

2 HCl + Pb (N03)2 = 2 (HNO3) + Pb CI2. 

Se O2 (selenious acid) + H2S (hydric sulphide) — Se S2 + 2 
(H2O). 

Ba Se O4 (baric seleniate) + 4 HCl = Se O2 + Ba CI2 + 2 
(H2O) + CI2. 

Te O2 (tellurous acid) + 2 H2S = Te S2 + 2 (H2O). 

Pb (N03)2 + 2 (Na HO) (sodic hydrate) = Pb (H0)2 + 2 Na 
NO3. 

Pb (N03)2 + H2 SO4 = H2 (N03)2 + Pb SO4. 

PCI3 + 3 H2O = P (HO)3 + 3 HCl. 

BCI3 (boric chloride) + 3 (H2O) = B (H0)3 + 3 (HCl). 

Cu SO4 + 2 (KHO) = Cu (H0)2 + K2 SO4. 

3 (Si F4) (silicic fluoride) + 2 (H2O) -= 2 (H2 Si F6) + Si02. 

Mn SO4 (manganic sulphate) + 2 Na HO) = Mn (H0)2 (man- 
ganic hydrate) + Na2 SO4. 

Sb2 (antimony) + 6 (H2 SO4) = Sb2 (SO4) 3-^6 H20 + 3 
(SO2). 



75 

ZnS04 + 2 (KHO) = Zn (H0)2 + K2 SO4. 

Sb2 S3 + Fe3 = Sb2 + 3 (Fe S). 

Sb2 S3 + 6 (HCl ) = 2 (Sb CI )3) + 3 (H2S). 

Co (N03)2 + 2 (Na HO) = Co (H0)2 (cobaltic hydrate) + 2 
(Na NO3). 

Mn SO4 + (NH4)2 C03 (ammonic carbonate) = Mn CO3 + 
(NH4) 2 SO4. 

2 HCl + Sn = Sn CI2 (stannous chloride) + H2. 

3 Fe SO4 + Au CI3 (auric chloride) = Fe CI3 + Fe3 (SO4) 

3 + Au. 

Ba (N03)2 + (NH4)2 CO3 = Ba CO3 + 2 (NH4) (NO3) 
(ammonic nitrate). 

HNa2 PO4 (hydro di-sodic phosphate) + 3 (Ag NO3) = Ag3 
PO4 (argentic phosphate) + 2 Na NO3 (sodic nitrate) + H 
NO3). 

Hg20 (mercuric oxide) + 2 HCl = 2 (Hg CI) + H2O. 

2 H (CN) (hydric cyanide) + 2 (Hg (N03)2 = (mercuric cyan- 
ide) 2 Hg + 2 H (NO3). 

Ca SO4 + (NH4)2 CO3 = Ca SO4 + (NH4)2 (SO4). 

Hg SO4 -I- Hg + 2 Na CI = 2 (Hg CI) + Na2 SO4. 

Sr (N03)2 + Ca SO4 = Sr SO4 + Ca (N03)2. 

Al SO4 + 2 (NH4) (HO) --= Al (HO2) + (NH4) 2SO4 (am- 
monic sulphate). 

HCl + Ag NO3 = HNO3 + Ag CI. 

H2S + 2 (Hg NO3) (mercurous nitrate) = Hg2 S + 2 (H 
(NQ3).) 

H2S + Pb (N03)2 = 2 (H (NO3) ) + Pb S. 



76 

HCl + Hg (NO3) = H NO3) + H^ a (mercurous chloride). 

2 (Na CI) + Hg SO4 = Hg CI2 + Na2 SO4. 

Hg CI2 + 2 (NH3) = Hg NH2 (double chloride of mercury 
and hydrogen) + (NH4) CI. 

2 KI + Pb (N03)2 = 2 KNO3 -r Pb I2. 

2 (Na CI) -f Hg SO4 = Hg CI2 + Na2 SO4. 

2 Sn CI (stannous chloride) + H2 S= Sn S + 2 (HCl). 

Sn CI2 (stannic chloride) + H2S = Sn S + 2 (HCl). 

Sn CI2 + 2 KHO = Sn (H0)2 + 2 (KCl.) 

Hg CI2 + Cu == Hg + Cu CI2. 

2 Ag NO3 + H2SO4 = Ag2 SO4 + 2 HNO3. 

Ag NO3 + (NH4) (HO) = Ag HO + NH4 NO3. 

Sr CI2 + Ca SO4 ^ Sr SO4 + Ca CI2. 

Ba CI2 + 2 Na HO = Ba (H0)2 + 2 (Na CI). 

Ca CI2 + (NH4)2 CO3 Ca CO3 + (NH4)2 CO3. 

Al CI2 + 2 (NH4) HO = Al (HO) 2 + 2 (NH4) CI. 

Cu SO4 + 2 KI = Cu I + K2 SO4. 

Hg CI2 + 2 KI =Hg I2 + 2 KCl. 

Cu SO4 + H2S = Cu S + H2 SO4. 

Au CI3 + 3 KI = Au I3 + 3 KCl. 

Pt CI4 + 4 KI = Pt I4 4- 4 KCl. 

Hg CI2 + H2S = Hg S + 2 HCl. 

2 Au CI3 + 3 H2S = Au2 S3 + 6 HCl. 



77 
Sn CI2 (stannic chloride) + H2S = Sn S + 2 HCl. 
Sb2 S3 + 6 HCl = 2 Sb CI3 + 3 H2S. 
2 HCl + Sn = Sn CI2 + H2. 
(Ag NO3) + CI Na = CI Ag + NO3 Na. 
PO4 Na H + 3 Ag NO3 = PO4 Ag3 + 2 Na PO4 +HNO3. 
Hg2 O =- Hg + Hg O. 
Hg2- + 2 HCl = Hg2 CI2 + H2O. 

Hg (N03)2 (H20)3 + nH20 = Hg2 NO3HO + NO3H + 
(n + 2) H2O. 

2 H (CN) + Hg2 (N03)2 = Hg (CN)2 + Hg + 2 HNO3. 

Hg2 (N03)2 + 2 Na CI = Hg2 CI2 + 2 Na NO3. 

2 Hg (NO3) + H2SO4 + 2 Na CI + H2O = Hg 2 CI2 + 

Na2 SO4 + 4 HNO3. 

3 AI2 O3 + 3 Si ^4 = AI2 O3 (Si 02)3 + 2 AI2 F6. 
5 Si O2 + 2 AI2 ¥6 = 2 (AI2 O3 Si O2) + 3 Si F4. 
3 Si F4 + 2 H2O = 2 H2 Si F6 + Si O2. 

2 HSi F5 + 2 KHO = 2 K Si Fs + 2 H2O. 

2 HSi F5 + 6 KHO = 6 KF + 4 H2O + Si O2. 

3 Ca F2 + B2O3 =-- 3 Ca O + 2 BF3. 
2 BF3 + 3 H2O = B2 O3H6F6. 

4 (B2O3H6F6) = B2O3 + 9 H2O + 6 (HBF4). 

Fe S + H2SO4 = H2S + Fe SO4. 



78 
Sb2 S3 + 6 HCl = 3 H2S + 2 Sb CI3. 
H2S + 03== H2O + SO2. 
N2O3 + 6 H2S = 2 NH3 + 3 H2O + S6. 
Sn + H2S = H2 + Sn S. 

2 Fe S + O3 = Fe2 O3 + S2. 

3 Ca O + S6 = Ca S2O3 + 3 Ca S2. 
Ca S2 + 2 HCl = Ca CI2 + H2S + S. 

2 (Fe SO4) + O = Fe O3 (803)2. 

Fe S2 + H2 O + O7 = Fe SO4 + H2 SO4. 

3 SO2 + H2 (N03)2 + 2 H2O = 3 (H2SO4) + 2 NO3. 
NO2 + SO2 + H2O = NO + H2SO4. 

2 NO2 + 2 SO2 H- H2O = 2 (NSO4) H2O. 

2 (NSO4) H2O + H2O = 2 NO + 2 (H2SO4). 

3 SO2 + H2(N03)2 + 2 H2O = 2 NO + 3 (H2SO4). 
2 SO2 + 2 NO2 + 2 H2O = 2 (H2SO4) + 2 NO. 

2 Ag + 2 (H2SO4) = Ag2 SO4 + 2 H2O + SO2. 

Mn O2 + H2SO4 = Mn SO4 + O + H2O. 

2 Cr O3 + 3 (H2SO4) = Cr2 O3 (803)3 + O3 + 3 H2O. 

2 (Fe 8O4) + heat = Fe2 O3 + 8O2 + SO3. 

K2 8O4 + C4 = K28 + 4 CO. 

2 Ca 8 + O4 = Ca 82O3 + Ca O. 

CaS203 + Na2 CO3 = Ca CO3 + Na2 S2O3. 



79 

2 Ag CI + Na2 S2O3 = 2 Na CI + Ag2 S2O3. 

3 SO2 + Zn2 = Zn OSO2 + Zn S2O3 + ZO3. 

4 {Na2 S2O3 5 H2O) = 20 H2O + 3 (Na2 SO4) + Na2 S5. 

3 (K2O) (H2O) (S02)2 + S = 2 (K2S3O6) + K2OSO2 + 
3 H2O. 

H2S3O6 = H2SO4 4- SO2 -f S. 

Fe2 C16 + 2 (Na2 S2O3) = Na2 S4O6 + 2 Fe CI2 + 2 NaCl. 

5 H2S + 5 SO2 = H2S5O6 + 4 H2O + Ss. 
2 CS2 + 2 H2S + Cu6 = 6 Cu S + C2 H4. 
CS2 + 2 NH3 = H2S + NH3 HCNS. 
K2CS3 + 2 HCl = H2CS3 + 2 KCl. 
K2CS3 + 3 H2O = K2CO3 + 3 H2S. 

2 S2CI2 + 2 H2O = 4 HCl + SO2 + S3. 
H2SO3 + H2O + 2 SO2 = 2 (H2SO4) + S. 
Pb S2O4 + H2S = H2S2O4 + PbS. 

2 HPO3 + C6 = 6 CO + H2 + P2. 

3 Ca (P03)2 + 2 (H2SO4) = Ca (H2 (P03)2)2 + 2 (Ca SO4). 
3 Ca (P03)2 + Cio = 3 Ca (P03)2 + 10 CO + P4. 

3 Ca (P03)2 + 6 HCl + C8 = 3 Ca CI2 + 8 CO + H6 + P2. 

3 H2 (P03)2 + 3 (Ag2 (N03)2 + 3 NH3 = 3 Ag2 (P03)2 + 
3 NH3H2 (N03)2. 

2 Na2 OH2 (P03)2 + 3 (Ag2 (N03)2) = 3 Ag2 (P03)2 + 2 
(Na2 (N03)2) + H2 (N03)2. 



80 

2 Na2 (P03)2 + 2 (Ag2 (N03)2) = 2 Ag2 (P03)2 + 2 (Naa 

(N03)2). 

(Na 0)2 {NH4)2 H2 (P03)2 + 3 (Ag (N03)2) = Na2 (N03)2 
+ (NH4)2 (N03)2 -h H2 (N03)2. 

Na2 (P03)2 + Ag2 (N03)2 = Ag2 (P03)2 + Na2 (N03)2. 

3 (Cu SO4) + 2 PH3 = 3 (H2SO4) + P2CU3. 
PCI5 + H2O = PCI3 O 4- 2 HCl. 

3 PCls + 3 H2B2O4 = 3 PCI3 + 6 HCl -f- B2O3. 

PCI5 + H2S = PCI3 S + 2 HCl. 

2 PC3S + 6 Na2 O == 6 Na CI + 3 Na2 P2O4S2. 

2 PCI3 + 3 H2S ^ P2S3 + 6 HCl. 

2 NH3 + P2O5 = H2O + N2 (H0)4. 

PCI3 + 3 NH3 = 3 HCl + N3H6PO. 

PCI3 S + 3 NH3 = 3 HCl + (NH3)2PS. 

PCI5 + 2 NH3 = 2 HCl + N2H4PCI3. 

N2H4PCI3 + H2O = N2H3PO + 3 HCl. 

N2H3PO + heat =: NH3 + NPO. 

As2 O3 + C3 = As2 + 3 CO. 

As2 O3 + H2ON2O5 + 2 H2O = N2O3 + 3 H2OAS2 O5. 

Zn3 As2 + 3 (H2SO4) = 2 As H3 + 3 (Zn SO4). 

2 As H3 4- 06 = As2 O3 + 3 H2O. 

As2 O3 + Zn6 + 6 (H2SO4) = 2 As H3 + 6(Zn SO4) + 
3 H2O. 



\ 



81 

2 As2 O3 + S7 = 2 As2 S2 + 3 SO2. 

Fe S2 Fe As 2 + 2 Fe S2 = 4 Fe S + As2 S2. 

3 As2 O3 + 2 HCl = 2 (As3 CI O4) + H2O. 
S9 + 2 As2 O3 = 2 As2 S3 + 3 SO2. 

2 Na2 H2OAS 06 + 7 H2S = 8 H2O + 2 Na2 As2 S6. 
2 Na2 As2 S6 + 4 HCl = 4 Na CI + 2 H2S + 2 As2 S5. 
Ca CO3 + 2 NH4CI = Ca CI2 + CO3 (NH4)2. 
Heat + 3 Ca CI2 O2 = Ca (CI 03)2 + 2 Ca CI2. 

2 Ca S + 2 H2O = Ca O2 H2 + Ca O2H2 + Ca S2H2 

3 Ca O2H2 + 6 S2 = 2 Ca S5 4- Ca S2O3 + 3 H2O. 

2 P04Mg NH4 (H20)6 + heat = Mg2 P2O7 + 2 NH3 + 13 

H2O. 

HKO+ K = K2O + H. 

K2CO3 + Ca H2O2 = 2 KHO + Ca CO3. 

SO4K2 + Ba (H0)2 ^S04Ba + 2 KHO. 

N03Na + CI K = NO3K + CI Na. 

NH3 + K = NH2K + H. 

Heat + S NH2K = NK3 + 2 NH3 

(CN)6 Fe K4 + CO3K2 = 5 KCN + CNKO + Fe + CO2. 

KOCN + 2 H2O = CO3HK + NH3. 

Heat + 3 KCl O = 2 KCl + CI O3K. 

(CI 03)2 Ca + 2 KCl = 2 KCl O3 + Cb Ca. 

3 Br2 + 6 KHO = 5 KBr + KBr O3 + 3 H2O. 



82 
S2K2 + 2 HCl = SH2 + 2 KCl + S. 
SO4K2 + HCl = SO4KH + CI K. 
SO4H2 + CI Na = S04Na H + HCl. 
Na HSO4 + Na CI = S04Na2 + HCl. 
Heat + 2 S04Na H= S207Na2 + H2O. 
Na2 HPO4 + NO3H = NOsNa + P04Na H2. 
Na2 HPO4 + HONa = P04Na3 -f H2O. 
Na2 HPO4 + CI NH4 = P04Na (NH4) H + CI Na. 
Ca CO3 + 2 HCl = Ca CI2 + H2O + CO2. 
4 H2O + C3 = CO2 + 2 CO + H8. 
Si3 H4O5 + 12 KHO = 3 (2 K2Si O2) + H6 + 5 H2O. 
2 (NH3HCI) + Ca O = Ca CI2 + H2O + 2 NH3. 

2 NH3 + CaO + 08 = Ca ON2O5 + 3 H2O. 
KNO3 + H2SO4 = HNO3 -f- KHSO4. 

4 (H2(N03)2) + Cu3 = 3 (Cu(N03)2) + 2 NO + 4 H2O. 

3 N2O3 + H2O = H2 (N03)2 + 4 NO. 
2 NH3 + N2O3 = N4 + 3 H2O. 

2 (NH3HCI) + K2ON2O3 = N4 + 2 KCl + 4 H2O. 
H2 (N03)2 -i- As2 O3 = H2OAS2 06 + N2O3. 

3 NO2 + H2O = NO + 2 HNO3. 
NO + 2 (HNO3) = 3 NO2 + H2O. 

2 N2O2 + 4 (KHO) = 2 K + K2 (N03)2 + 2 H2O. 



83 

2 H2 (N03)2 + Sn = 2 H2O + 4 NO2 + Sn O2. 

3 {H2 (N03)2) + Ag4 = 3 H2O + N2O3 4- 2 (Ag2 (N03)2). 

4 (H2 (N03)2) + Cu3 = 4 H2O + 2 NO + 3 (Cu (N03)2). 

5 (H2 (N03)2) + Zn4 = 5 H2O + N2O + 4 (Zn ON2O5). 

2 Na CI + Mn O2 + 2 (H2SO4) = Na2 SO4 + Mn SO4 + 2 
H2O + CI2. 

Mn O2 + 4 HCl = Mn CI2 + 2 H2O + CI2. 

4 (Ca (HO) 2) + CI4 = (Ca OCI2 O + Ca CI2 + 2 CaO) + 4 
H2O. 

(Ca OCI2O + Ca CI2) + 2 (H2SO4) = 2 (Ca SO4) + 2 H2O 

+ CI4. 

2 Na CI + H2OSO3 = 2 HCl + Na2 OSO3. 

Fe + 2 HCl = Fe CI2 + H2. 

Na + HCl = Na CI + H. 

Ag2 O + 2 HCl = H2O + 2 Ag CI. 

Cu2 O + 2 HCl = H2O + Cu2 CI2. 

Sb2 O3 + 6 HCl = 3 H2O + 2 Sb CI3. 

Mn2 O3 H- 6 HCl = 3 H2O + 2 Mn CI2 + CI2. 

Mn O2 + 4 HCl = 2 H2O + Mn CI2 + CI2. 

Hg O + CI4 = Hg CI2 + CI2O. 

CI2 O + 2 HCl = H2O + CI4. 

HNO3 + 3 HCl = 2 H2O + NOCI2 -f CI. 

NOCI2 + H2O = 2 HCl + NO2. 

6 KHO + Br6 = 5 KBr + KBr O3 + 3 H2O. 



84 

2 KBr + Mn O2 + 2 (H2SO4) =K2S04 + Mn SO4 + 2 K2 
O + Br2. 

6 H2O + Br6 + P3 = 3 H2PO4 + 6 HBr. 

2 Na I + Mn O2 + 2 (H2SO4) = Na2 SO4 + Mn SO4 + 2 
H2O + I2. 

6 KHO + 16 == 5 KI + KIO3 + 3 H2O. 

5 KI + KIO3 + 6 HCl = 6 KCl + 3 H2O + 16. 

Na2 (103)2 + 2 Na2 O + CI4 = Na2 (104)2 + 4 Na CI. 

2 Na2 (104)2 + 4 (Ag NO3) = 2 Ag2 (104)2 + 4 (Na NO3). 

2 Ag (104)2 + H2 (N03)2 = Ag2 OI2O7 + Ag2 (N03)2 + 
H2O. 

2 (Ag2 (104)2) + H2O = O7 2 Ag2 (104)2 + H2IO8O7. 

8 H2O + Iio + P2 = 10 HI + 3 H2 (P03)2. 

4 KI + 3 H2 (P03)2 = 4 HI + 2 K2H2 (P03)2. 

NHI2 = N + HI + I. 

Fe I2 + Fe2 16 + 4 (K2CO3) = 8 KI + Fe OFe2 O3 + 4 
CO2. 

Ca F2 + H2SO4 = Ca SO4 + 2 HF. 

2 Ca F2 + Si O2 + 2 (H2OSO3) = 2 (Ca OSO3) + SI4 + 2 
H2O. 

Si F4 + 2 H2O = Si O2 + 4 HF. 

Hg SO4 + Hg + 2 Na CI = Hg2 CI2 + S04Na2. 

Hg2 CI2 + 2 NH3 = Hg2 CI NH2 + NH4 CI. 

2 Na CI + Hg SO4 = CI2 Hg + SO4 Na2. 

Hg CI2 + 2 NH3 = Hg NH2CI + NH4CI. 



85 

Hg CI2 + Cu = Hg + Cu CI2. 

3 Hg SO4 + 2 H2O = Hg3 S06 + 2 H2 SO4. 

PbS + 30 = PbO + SO2. 

Pb S + 2 O2 = Pb SO4. 

Pb3 O4 + 4 HNO3 = 2 Pb (N03)2 + Pb O2 + 2 H2O. 

Pb O2 + 4 HCl = Pb CI2 + CI2 + 2 H2O. 

3 Bi CI3 + 4 H2O = Bi3 O2CI3 (H0)2 + 6 HCl. 

2 Cu O + Cu2 S = 2 Cu2 + SO2. 

Fe + SO4 Cu = SO4 Fe + Cu. 

Cu2 H2 + 2 HCl = Cu2 CI2 + 2 H2. 

2 Cu SO4 + 4 KI = Cu2 I2 + I2 + 2 K2SO4. 

2 HNa2 PO4 + 3 Cu SO4 = Cu3 (P04)2 + 2 Na2 SO4 + 
H2O2 SO4. 

C + CO2 = 2 CO2. 

C + H2O = CO + H2. 

2 Fe2 H606 — 3 H2O = Fe4 O9H6. 

3 Ba CO3 + Fe2 C16 = 3 CO2 + Fe2 O3 + 3 Ba CI2. 

Fey Cyi8 + 12 KHO = 3 Fe Cy6 K4 + 2 Fe2 O3 + 6 H2O. 

Fe2 Cyi2 + 3 Fe CI2 = Fes Cyi2 + 6 KCl. 

Fes Cyi2 + 8 KHO = 2 Fe Cy6 K4 + Fe2 H606 + 
Fe H2O2. 

Fe2 C16 + 6 KI = 2 Fe I2 + I2 + 6 KCl. 

Fe S + 2 HCl = Fe CI2 + H2S. 



86 

Fe2 C16 + H2S = 2 Fe CI2 + 2 HCl -f S. 

2 Fe SO4 = SO2 + Fe2 O2SO4. 

AI2 O3 + 3 C + 3 CI2 = AI2 C16 + 3 CO. 

AI2 C16 + ( (NH4)2 S)3 + 6 H20= AI2 06H6 + 3 H2S + 
6 NH4CI. 

Cr (804)3 + 3 (NH4)2S + 6 H2O = Cr2 H606 + 3 (NH4)2 
SO4 + 3 H2S. 

2 Cr O3 + 12 HCl = Ct2 C16 + 6 CI + 6 H2O. 

2 Cr O3 + 6 HCl + 3 H2S = Cr2 C16 + 3 S + 6 H2O. 

Cr O4K2 + 2 Na CI + 2 H204Cr O2CI2 + SO4K2 + S04Na2 
+ 2 H2O. 

2 Cr O3 + 3 H2SO4 = Cr2 (804)3 + 3 O + 3 H2O. 

K2Cr2 O7 + 12 NH4F + 7 H28O4 = 2 Cr F6 + K2SO4 + 
6 (NH4)2804 + V H2O. 

C02CI6 + 3 Ba CO3 = C02 O3 + 3 CO2 + 3 Ba CI2. 

Mn 8 + Co CI2 = Mn CI2 + Co 8. 

3 K2Mn O4 + 2 H2O = K2Mn2 08 + Mn O2 + 4 KHO 
Ba 8 + 2 HNO3 = (N03)2Ba + H2S. 

S04Ba + 2 C2 = 8Ba + 4 CO. 

6 Ba H2O2 + 6 I2 = Ba (103)2 + 5 Ba I2 + 6 H2O. 

Miscellaneous principles and facts are as follows : — 

Quick-lime, phosphoric anhydride, and sulphuric acid (con- 
centrated) absorb with avidity moisture from the air. 

Hydrogen is the lighest substance known, being a rare gas; 
while platinum is the heaviest, except one or two rare metals. 

8odium and potassium, and not aluminium, are the lightest 
metals, being light enough to float upon water. 



87 

Hydrogen gas has not been liquefied by pressure, but car- 
bonic acid gas and ammonia gas have been, and can be without 
difficulty, with the proper apparatus. Hydrogen gas has the 
property of passing through hot, but not cold, iron, palladium,- 
and platinum. Hydrogen is combustible with oxygen, chlorine, 
and a few other elements by the action of heat ; or, indirectly, 
by placing certain compounds in contact with one another. 
Hydrogen and chlorine, when mixed and exposed to sunlight, 
explode violently with formation of hydrochloric acid. Colored 
textile materials are bleached by the action of chlorine or by 
ozone; because these two elements have a strong affinity for 
hydrogen, and because all aniline and vegetable colors are due 
to the presence of hydrogen. Chlorine, when absorbed by 
water, and placed in the sun, will decompose a portion of the 
water uniting with the hydrogen and liberating the oxygen. If 
hydrogen and iodine are passed over platinum, heated to red- 
ness, they combine, forming hydriodic acid; whereas water is 
decomposed into hydrogen and oxygen gases, if passed through 
red-hot iron tubes. About the only chemical which acts upon 
glass is hydrofluoric acid, and the action is so great that in a 
few minutes a surface of polished glass looks like ground glass. 
Although all water, in nature, is composed of oxygen and hydro- 
gen, it also contains free oxygen absorbed, which may be 
expelled by heat, or a vacuum pump, or absorption by some 
chemical with which it has a strong affinity. 

The temperature of a flame remains at that at which com- 
bustion occurs, so that a very slight lowering of the temperature 
will extinguish it; therefore a piece of metal gauze, put through 
a gas flame, will prevent the flame from coming through the 
gauze, the gauze being made of any metal. 

At the ordinary temperature, phosphorus will unite gradually 
with oxygen, becoming white; and if rubbed, will burst into a 
flame, and be converted into a cloud of white fumes of the 
oxide of phosphorus; and similarly all metals can be made to 
combine with oxygen, upon .condition that the temperature is 
sufficiently high. 

One-thousandth of a pound of coal gas, when exploded with 
the proper proportion of air, is equivalent to a force which will 
raise a weight of 48 pounds through the space of one foot, 
showing that the explosion of coal gas, by an electric spark, for 
instance, produces great power. 

Water, although apparently incompressible, is compressible 
to the extent that were the atmospheric pressure of 15 pounds 
to the square inch doubled, 1,000,000 volumes would become 
less by 50 volumes. It is a very bad conductor of heat and of 



88 

electricity; and is not known to conduct the latter unless by it 
decomposed more or less into hydrogen and oxygen gases. Above 
4° C. it expands by heat, and it is a remarkable fact that below 
that temperature it also expands, but it always resumes the, 
same density at any given pressure and temperature. 

Certain solids are not only soluble in water, but also certain 
liquids, as alcohol, ether and acetic acid; and also gases, as 
ammonia and hydrochloric acid and nitric acids; the rate and 
degree of solubility depending upon the nature of the gas, the 
temperature of the water, and the pressure upon the surface of 
the water. 

An atmosphere or ocean of air surrounds the earth, and 
varies in pressure from the top to the bottom, being greatest at 
the latter limit, and equal to 15 pounds per square inch. 

The atmosphere contains intimately mixed nitrogen and 
oxygen, principally, and traces of water vapor and carbonic acid 
gas. 

The atmosphere has the property of a lens, in that after the 
sun has actually '' set " it may still be seen, because the air re- 
fracts or bends the rays downward. 

Carbon occurs in three distinct physical states — as animal 
or vegetable charcoal or coke ; as representing one state 
properly called charcoal; as graphite and as diamond; so that 
when any one is burned, in presence of pure oxygen, car- 
bonic di-oxide alone is formed. 

Rain-water, when passing through the air, absorbs such 
impurities as carbonic acid gas, gases from chemical works, 
factories, &c. 

In addition to phosphorus having the property of lighting 
at the ordinary temperature, especially if rubbed slightly, phos- 
phoretted hydrogen, in escaping from a tube, will ignite im- 
mediately and continue to burn as long as the supply lasts. 

Litmus is a liquid having the property of turning red when 
mixed with an acid; of turning blue when mixed with an alkali; 
and being changed from neither red nor blue when treated with 
any other known substance. 

The combustion of magnesium metal in air produces in- 
tensity of light equal to that of the arc lamp or " calcium " 
light, the product being the infusible oxide of magnesium, called 
magnesia. 

Zinc becomes brittle at the temperature of about 205° F. 

Certain chemical elements can be combined or separated by 
the force of heat, electrolytic action, light, or by contact with 
other elements or compounds, or by the combination of those 
forces. 



89 

Although mercury is the only liquid elemental metal, 
viscous or soft metallic substances may be obtained, as amal- 
gams, by mixing certain other metals with mercury. 

Sodium has such a strong attraction for mercury as to com- 
bine therewith, to form an amalgam, with a brilliant light and 
hissing sound. 

The most abundant element in the world, except oxygen, is 
aluminium, and exists in combination with oxygen as an oxide, 
together occasionally with small quantities of potassium, iron, 
calcium and magnesium. Aluminium is only about two and 
one-half times as heavy as water; while iron is eight times as 
heavy as water, and platinum is twenty-one times as heavy as 
water. 

Although ordinary iron has the property of receiving a de- 
posit of copper when immersed in a solution of a copper salt, yet 
it loses this property if first mometarily dipped in strong nitric 
acid and then washed. 

Wrought iron, cast iron and steel differ from one another 
according to the amount of carbon they contain ; wrought iron 
containing the least and cast iron the most ; while the temper of 
steel depends upon the degree of heat from which it is suddenly 
cooled. The electric conductivity of steel increases with its 
temper. 

These different iron mixtures with carbon have different 
electrical and heat conductivities and powers of magnetic 
reception. 

Nickel, like iron, is more easily fusible when containing a 
small quantity of carbon, and will also, like iron, at a red heat, 
decompose water into hydrogen and oxygen. 

Cotton, linen and wood are rendered practically incom- 
bustible when treated (in the manner of starching) with tungs- 
tate of soda, which will also serve as a mordant in dyeing. 

A bar of pure tin, when bent, emits a peculiar, soft, crack- 
ling sound. 

When gold is rolled sufficiently thin, it will transmit light, 
and will have a color dependent upon the thinness of the foil. 

Gold-leaf, which is green by transmitted light, becomes ruby 
red when heated to 316° F. 

Platinum has such a power of concentrating oxygen on its 
surface, that when a coil thereof is heated in an alcohol flame, 
and the flame extinguished, the red-hot platinum will continue 
to be red hot, even in the absence of the flame. The platinum 
must remain over the wick. 

"Platinum black" absorbs more than 800 times its volume 
of oxygen. 



90 

There are no two substances having exactly the same de- 
gree of hardness; and of two substances, that one which leaves 
a mark upon the other, by friction, is the harder. Among the 
hardest substances are diamond and steel, and among the 
softest solids are soapstone, potassium, graphite and lead. 

A weak solution of chloride of cobalt is pink. A con- 
centrated solution is blue. Paper saturated therewith is light 
pink and turns blue when heated. 

Sulphur, at the ordinary temperature, is hard, like a stone. 
When first heated, it is very thin, and when heated higher it is 
viscous or very thick. At a still higher temperature, the fused 
sulphur becomes again thin, and in cooling, the same change 
takes place. 

If oxygen i volume, and hydrogen 2 volumes, are mixed in 
a vessel and exploded — for instance, by a spark — water vapor 
is produced which has a volume of only f the gases when not 
combined, /. ^., the volume is only 2. If i volume of chlorine 
and T of hydrogen are combined, the result is 2 volumes. In 
general, the volume after combination is 2, even if the volume 
of the elements before chemically combining, as in N2 O3 (nitro- 
gen peroxide), is 5. 



91 

CHAPTER XIII. 

Principles in Electricity as Tools for Making 
Scientific Inventions. 



Electricity is a form of force. What it is further than this 
no one knows, any more than one knows what gravitation is. 

Two general classes of electricity are generally named 
static and dynamic, often called galvanic. Similarly, we could 
speak about gravitation. The words explain the difference. 
Static electricity is the condition where a charge tends to 
flow, but cannot because the circuit is not complete. It is 
electricity at rest. If a weight rests upon the floor, there is 
static gravitation. The weight tends to move, but cannot. 
Make a hole in the floor and it moves. The floor acts as a 
resistance. So with static electricity; it does not move because 
there is too great a resistance; there is no proper conductor upon 
which it can move. As soon as a conductor is provided, the 
current flows. This current is called dynamic. Static electricity 
is often spoken of as frictional; but dynamic electricity 
may also be frictional. However, for the inventor, he cares not 
for names, and therefore each principle and fact will be stated 
by the words which convey the information in as simple 
a manner as possible. Gravitation will not travel along a 
wire and back again to the generating point, but an electric 
current will, and the wire may be tapped at any point and the 
electric energy converted by the proper means into mechanical, 
chemical, magnetic and light energy. If the wire is completely 
broken, the generator of the electricity maintains the wires 
charged, but performs no work. 

Electricity is generated in the following different ways : 
By friction or when two substances are rubbed together; com- 
pression of substances ; variation of temperature upon tour- 
maline; fracture of substances; solidification of a substance from 
a state of fusion or gas; chemical action in a primary or secondary 
battery; combustion of carbon, the same being electrified nega- 
tively, and the resulting carbonic acid, negatively; by evapor- 
ation of a liquid. Fog, snow and rain are found to be 
charged. The clouds are most always electrically charged. 
It is generated by the relative motion of electro or permanent 
magnets; by induction from any other neighboring circuit; by 
certain animals and fish ; by heat, as when two different metals 
are touched together in a flame; and by friction of clouds, 
producing lightning. 



92 

Light is claimed to be converted into electricity by coating 
opposite sides of a plate of glass with sheets of tin-foil (bright 
on one side and dull on the other) and exposing the dull side to 
the direct rays of the sun and dipping in alcohol. The electro- 
motive force or pressure is about .06 volt. The dull side of one 
sheet of foil should face a bright side of the other sheet. The 
current passes through a wire connecting the sheets of tin- 
foil. 

Coat two silver plates with silver salts or aniline dyes, and 
immerse in a conducting liquid, and it is found that a small 
current is generated, if electrically connected, while one plate is 
exposed to light and the other placed in the dark. 

Slight electric currents may be obtained from the earth by 
connecting a well-insulated and long-distance telegraph line to 
ground at both ends, omitting all electric generators. A delicate 
galvanometer needle is deflected, but resumes its original 
position when the line is interrupted. The amount of current 
depends upon the condition of the tides; upon the relative 
temperatures of the two points of the earth at which the line is 
grounded; and upon the condition of the sun's spots. The 
direction of the current is easterly, and the maximum is in the 
direction from N. W. to S. E. ; but this rule is found to be 
general and not without exception. 

The generation of electricity by chemical action consists in 
a transferring of the atoms from one compound or element to 
other elements or compounds. When this change takes place, 
an electric current is produced. The chemical force is changed 
into electrical force. This current may then be changed again 
into chemical force by passing it through a solution of any given 
compound, whose atoms either separate or rearrange them- 
selves into other compounds, or unite with the atoms of one or 
more other compounds. These are principles, but no one 
knows whether the chemical and electrical forces are one and the 
same thing disguised to human eyes. 

Electrical conductors are as follows, being approximately less 
and less in the order named : Metals, pure graphite, acids, aqueous 
solutions of acids, salts or hydrates; animals, vegetables, water, 
snow, linen and cotton. The non-conductors are principally : 
Metallic oxides; ice at the lowest possible temperature; caout- 
chouc, dry gases or mixture of gases; dried paper; silk, precious 
stones; glass, wax, sulphur, resins, amber and shellac; alcohol, 
flour of sulphur and powdered glass. 

Carbon being of high resistance, its mixture with a non- 
conductor increases the resistance of the former and lowers that 
of the latter as far as the final result is concerned. Similarly, 



93 

fine metallic particles mixed with carbon result in a substance 
of different resistance from either; in general, substances of 
different resistance (or conductivity) may be obtained of any 
desired degree by mixing different substances in the same or 
different proportions. The result will always be a resistance 
differing from that of either constitutent. An illustration of the 
application of this principle is found in the invention of the 
present cheap commercial reduction of aluminium from its 
cheap oxide, which is a non-conductor, but mixed with carbon 
is practically a conductor. The passage of a heavy current 
heats the same to such a high a temperature that the oxygen 
leaves the aluminium and goes to the carbon, forming carbonic 
acid gas, which escapes, leaving the aluminium free. 

The relative conductivity of conductors is as follows : Silver 
being taken as the best and represented in value by loo. Cop- 
per is nearly as good a conductor, being represented by 99.9; 
gold by 80; sodium, 37; aluminium, 34; zinc, 29; cadmium, 24; 
brass, 22; potassium, 21; platinum, 18; iron, 17; tin, 13; lead, 
8; German silver, 8; antimony, 5; mercury, 2; bismuth, i; 
graphite, o. 

The relative conductivity of some liquids is indicated by 
calling that of silver 100,000,000,000,000. Cupric nitrate satur- 
ated solution in water would be represented by 8,900; cupric 
sulphate, saturated, by 5,420; sodic chloride, saturated, by 31,- 
520; ^inc sulphate, saturated, by 5,770; sulphuric acid, diluted 
so as to be 1.24 times as heavy as water, by 132,750; com- 
mercial nitric acid, by 88,680; and perfectly pure water, as 
obtained by distillation, by 7. 

Reference has been made to the action of light on the 
conductivity of selenium. Its conductivity is doubled in direct 
sunlight. Even gas light increases its conductivity. 

In the following principles relating to the electro-chemical 
generator and decomposition it is assumed that it is known that a 
device for carrying the above principles into effect consists of 
a vessel containing a liquid called conveniently the electrolyte 
and two pieces of solid material dipping therein, called the 
electrodes. A wire joining the electrodes and including or not 
including electric lamps, or bells, or motors, &c., is called a 
circuit. 

The electrolyte may be a single conducting acid, dilute or 
concentrated; or an aqueous or acid solution of a decomposable 
salt, oxide or hydrate. Usually, it cannot be a vegetable or 
animal substance. If of the same metal, a current is not pro- 
duced theoretically; but in practice, it is impossible to get two 
pieces which have the same molecular structure, temperature. 



94 

chemical constitution, &c., so that a very slight current may 
often be detected. Not only should the metals be different in 
order to obtain large currents, but the electromotive force 
(pressure) and current are dependent upon the particular metals 
joined in the same cell. If zinc and carbon are used as the 
electrodes in dilute sulphuric acid, for instance, there is more 
electromotive force than if iron is used in the place of zinc; 
again, the electromotive force is still less with lead. In the place 
of solid conductors, gases or even liquids may be employed, or the 
electrodes may be provided with a coating of a salt, oxide or similar 
decomposable compound. As far as the elements are concerned, 
the electromotive force is higher and higher according to the 
distance apart of any two of the following-named elements : 
Oxygen, sulphur, nitrogen, fluorine, chlorine, bromine, iodine, 
phosphorus, arsenicum, chromium, boron, carbon, antimony, 
silicon, hydrogen, gold, platinum, mercury, silver, copper, 
bismuth, tin, lead, cobalt, nickel, iron, zinc, manganese, 
aluminium, magnesium, calcium, barium, lithium, sodium, 
potassium. Example: If one electrode is oxygen (made for 
instance by using carbon which is exposed to air) the electro- 
motive force is much greater with a second electrode of lead 
than of silver. The electromotive force is the least with elec- 
trodes made of elements which are next to each other in the 
above list. The electromotive force is greatest between the 
first and last, namely, oxygen and potassium. In the above 
series dilute sulphuric acid is the electrolyte. The series varies 
a little with other electrolytes. 

The fact that the electromotive force increases under certain 
conditions is not necessarily a proof that more energy is obtained 
from certain amounts of chemical actions in a cell any more 
than that a locomotive necessarily does more work in going 
from New York to Philadelphia in two hours than in three. 
More work is done in the former case in a given interval, but 
not more total work. 

The principles upon which a cell in general produces a cur- 
rent may be explained thus: The structure in the first place is 
a conducting and decomposable liquid which serves as an elec- 
trolyte. The liquid if not decomposable is not operative. 
Thus, mercury is a conducting liquid, but does not serve as an 
electrolyte. Again, the liquid should be not only a compound, 
but a conducting compound. Oil is a compound, but no elec- 
trolyte. It is not a conductor. The electrolyte may consist of 
several liquids. 

The chemical actions which occur in a cell take place at the 
surfaces and often within the mass of the electrodes: but not much 



95 

beyond the surfaces. The maximum action takes place on 
those surfaces nearest together. The larger the amounts of 
surface exposed to the action of the electrolyte, the greater the 
current, but the electromotive force remains constant, which, 
however, may be increased by connecting two or more cells in 
series, /. e.^ by connecting electrically the negative electrode of 
one cell with the positive of the next cell, and so on. Illustra- 
tion: If each cell contains electrodes of carbon and zinc, the zinc 
of one cell is connected to the carbon of the next, which is con- 
nected to the zinc of the next, and so on, the final carbon and 
zinc being the terminals of the battery, which if connected by a 
conductor instantly allows the chemical actions to take place 
and a current to flow. If like electrodes are joined in sets a 
current is found by joining the sets. The electromotive force is 
not increased, but the current is. The product of the current 
by the electromotive force is equal to the amount of electrical 
energy, just the same that the product of the height of a column 
of falling water by the amount of water which falls equals the 
amount of work which the falling water performs. 

Sometimes cells may be electrically connected in a closed 
circuit without giving a current by connecting all the zincs and 
all the carbons into one set or closed circuit. Various combi- 
nations of the above elementary methods of connecting up cells 
may be made. Thus some cells of a given set may be joined in 
series and others in parallel, and still others in opposition, the 
resulting current being due to the nature of the combination. 

The current produced by the chemical action in a battery 
will produce chemical action in another battery, but only on the 
condition that the energy of the former current is greater than 
that of the latter. Illustration: Let the terminals of a sulphuric 
acid battery be dipped in dilute sulphuric acid. Hydrogen and 
oxygen are given off at the respective terminals, which will 
escape into the air or combine with the electrodes according to 
their chemical nature. If the terminals are platinum, the oxygen 
and hydrogen both escape, except that a small amount at the 
beginning will be mechanically absorbed by the platinum. If 
the oxygen and hydrogen unite with the electrodes in such a 
manner as to form insoluble compounds thereon, as will be the 
case with lead terminals, the same will act as a good cell itself 
after the said battery is taken away. Similarly, any secondary 
conducting terminals and any conducting decomposable elec- 
trolyte form more or less of a secondary cell after the primary 
charging battery is removed and the cell closed upon itself. 

Some cells give a constant current and some give a weaker 
and weaker current until the final is very weak. The latter 



96 

generally are formed with one electrolyte; the former with two, 
separated in such a manner that they can mix only very slowly, 
as may be done, for example, by means of a porous earthenware 
jar. When two electrolytes are employed, an electrode is placed 
in each. The reason why a single electrolyte cell forms a 
decreasing current is that bubbles of gas collect upon the sur- 
faces of the electrodes. As gases are bad conductors, the in- 
ternal resistance increases, thereby decreasing the current. The 
current becomes strong again upon removing the gases either 
mechanically or chemically. The greatest collection of bubbles 
is at that pole which in sulphuric acid or other decomposable 
compound of hydrogen is where the hydrogen is liberated. By 
means of the double electrolyte cell a chemical is furnished 
with which the hydrogen unites as soon as liberated, thereby 
preventing the formation of bubbles. Those liquids which can 
furnish oxygen, chlorine or similar substance with which hydro- 
gen will unite are suitable for the second electrolyte. Some 
such compounds are: Nitric acid, HN O3; aqueous or acid 
solutions of salts, such as potassic bichromate, potassic chlorate, 
sodic chloride, ammonic chloride, &". 

Almost any chemical reactions known in chemistry for 
producing either oxygen or chlorine are applicable in the cell 
for the chemical removal of hydrogen bubbles. The name 
given to the bad action of the bubbles is polarization, because 
it corresponds to electrically connecting the poles of a weaker 
cell in opposition. Two currents are tending to flow in opposite 
directions, the differences between the two being the resultant 
or useful current. 

Another chemical way of preventing the bubbles is by using 
as the second electrolyte those particular salts which liberate a 
pure metal instead of hydrogen. The metal forms a coating 
which is a good conductor; therefore the resistance is not 
increased. 

The following list of metals serves to predict upon which 
electrode the hydrogen is given off in a primary ceW. If any two 
are employed in the order named, the first one of the pair is the 
hydrogen electrode : Silver, copper, antimony, bismuth, nickel, 
iron, lead, tin, cadmium, zinc. 

Some of the ways in single electrolyte cells of removing the 
bubbles mechanically are by agitating the electrolyte; by 
rubbing the electrode, or by covering it with platinum black or 
similar substance, which will absorb the hydrogen, and by having 
a greatly enlarged electrode, especially as to the amount of sur- 
face exposed to the electrolyte in proportion to that of the other 
£lectrode. 



97 

Electrodes placed in the ocean form a good cell, because 
the motion of the salt water washes off the bubbles as soon as 
formed. 

Sometimes the polarization is so great with cells in series 
that it causes the poles of some of the cells to be reversed; but 
the poles of a single cell never become reversed. Short-circuit- 
ing is one of the principal causes of reversal. The polarization 
then becomes the maximum, causing the greatest counter- 
current. When the cells are not duplicates in size or chemical 
nature, &c,, reversal occasionally occurs. 

When common moist earth is mixed with ammonic chloride 
(sal ammoniac) and electrodes of copper and zinc are immersed 
therein, a cell is formed having but little polarization. The 
hydrogen bubbles are thought to be absorbed in the porous 
earth. Powdered carbon in large quantity serves as a partial 
depolarizer in view of the comparatively large amount of pores 
for absorbing the hydrogen, and because the oxygen absorbed 
from the air unites with the hydrogen. 

The forcing of air into a liquid through a tube, whereby the 
electrolyte is effectually agitated, assists greatly in depolarizing. 
The quiet addition of oxygen to the electrolyte by mixing without 
any chemical combination with the electrolyte does not assist in 
depolarizing. 

The generation of electricity by the use of oxygen in the air 
is obtained by using carbon as one of the electrodes and a metal 
as the other electrode. The oxygen is absorbed in the pores of 
the carbon and there unites with the hydrogen, which is liberated 
at the carbon electrode. The oxygen continually feeds itself 
from the air into the carbon. When the carbon is under such 
a condition as to receive no air, the weakness of the cell is very 
noticeable. 

Electrodes may be of the same conducting solid, if im- 
mersed in different liquids which are so arranged as to gradually 
mix. Example: Divide a vessel into two parts by an earthen- 
ware partition, and place potassic hydrate and sulphuric acid in 
the respective compartments. Place platinum electrodes there- 
in, and a cell is obtained. 

Different gases may also be employed in place of the liquids, 
but a liquid must also be used between the gases, and the elec- 
trodes must be in contact with both the liquid and the gases. 
Example : Invert tubes of hydrogen and oxygen respectively 
over and in dilute sulphuric acid, and use platinum electrodes 
v/hich pass up through the electrolyte into the gases. A cell is 
obtained, as may be known by connecting the electrodes electri- 
cally through a galvanometer. 



98 

Zinc is soluble in sulphuric acid, but when coated with a 
layer of mercury, as may be done by dipping it in mercury for a 
few minutes after having dipped it into some sulphuric acid, it 
becomes practically insoluble in the acid; but it may then be 
caused to. dissolve in the acid if connected electrically with 
some other metal or carbon also in the acid. 

It becomes of importance to study into the molecular actions 
which are thought to take place in the decomposition of a liquid 
by passing an electric current through it. Let sodic chloride 
(common salt) in solution in water be considered. It is supposed 
that the atoms of sodium and chlorine while in solution are 
not all permanently combined, but are continually uniting and 
separating, so that during any given minute there exists not only 
sodic chloride, but also the separated elements. When, how- 
ever, the salt is dried so as to become a solid, the chlorine and 
sodium unite permanently until again dissolved in water or 
other liquid. Again, the atoms of hydrogen and oxygen of 
liquid water are continually combining and separating, but 
in ice the atoms are permanently combined. So with all 
conducting compound liquids it is supposed that different atoms 
composing the same are both combined and separated, but all 
the time substantially as close together; /. <f., the atoms do not 
escape as a gas. This supposition is necessary or else it is 
difficult to grasp the reason why an electric current decomposes 
liquids. By the use of the supposition the phenomenon of 
electrolysis is easily explained. When the current passes 
through water, the atoms of hydrogen and oxygen being rela- 
tively electro positive and negative, become charged so that they 
go to the respective electrodes and remain separated as long as 
charged. They will go together again upon cutting off the cur- 
rent and allowing them to generate a current as in the ordinary 
oxy-hydrogen voltmeter. The supposition or hypothesis ex- 
plains also why a liquid becomes a better conductor when 
heated. The heat increases what might be called the liquidity 
of the liquid. It makes the force of cohesion less, so that the 
hydrogen and oxygen (in case of water) will more easily 
separate. It is thought from the above considerations that the 
atoms separate from one another under the influence of a cur- 
rent as a result of mechanical motion produced by the current. 
The theory explains all the phenomena of electrolysis. Solid 
compounds are not decomposable by the passage of a current 
because the atoms are permanently combined; they do not, as 
in liquids, alternately combine and separate. The force of 
cohesion between them is greater and greater the lower 
the temperature; but with liquids the forces of cohesion and 



99 

chemical attraction are more nearly balanced than in any other 
form, as pointed out in the chapter on heat. The force due to 
electrical molecular repulsion overcomes gradually the force of 
cohesion. It might properly be called heat without rise of tem- 
perature; because heat also causes decomposition of water. The 
electric current decomposes the water or other conducting com- 
pound liquids with practically no rise of temperature in com- 
parison with that of over i,ooo° required by heat. As far as 
total effects are concerned, however, heat and electric separation 
are similar. As soon as a compound arrives at a certain high 
temperature the decomposition takes place in the whole mass; 
but with the electric current the decomposition is very, very 
sloW; gradual and local. Deposition of metal from a solution of 
its salt may not only be effected by passage of a current through 
two electrodes separated from each other in the solution, but by 
the mere immersion of certain metals in the solution. When a 
rod of zinc is placed in an acid solution of stannous chloride, 
the tin leaves the chloride and forms in crystals upon the sur- 
face of the zinc. Mercury separates silver in large quan- 
tities and quite rapidly from a solution of argentic nitrate. 
Zinc in plumbic acetate soon looks like a beautiful tree 
of lead scales. The principle underlying the action is that 
the metal placed in the solution of a second metallic salt 
takes the place of said second metal. Thus, if iron is 
placed in cupric sulphate the equation is as follows: Fe 
(iron) plus CUSO4 (cupric sulphate) equals (copper) plus 
FeS04 (ferric sulphate). Consequently, in order to get out 
the copper from the solution, iron must be put in the place 
of the copper. 

An electric cell in which the electrolyte is an aqueous solu- 
tion of chromic chloride, and the electrodes, tin and platinum, 
gives no current at the ordinary temperature; but if heated con- 
siderably, a current is produced in a closed circuit. The chemi- 
cal action consists in the conversion of the tin into stannic 
chloride. When the cell is cooled, it returns to its original 
chemical condition, and when heated a current is again given 
off; and the operation may be repeated indefinitely without loss 
of material, provided the cell is made air-tight, so that no chlorine 
shall escape. When the tin is each time liberated from the 
stannic chloride it falls to the bottom as a metallic precipitate. 
The bottom of the cell should therefore be employed from the 
beginning as the support for the tin. This is an example of the 
conversion of heat into electricity. Another example is as fol- 
lows : The electrolyte is melted potassic nitrate; the electrodes, 
carbon and iron. The carbon unites with the oxygen from the 



100 

nitrate, forming a carbon di-oxide. The heated nitrate causes 
the conversion of heat into electricity. 

The obtaining of electricity by the consumption of carbon 
without heat is illustrated by the cell in which sulphuric acid is 
one electrolyte, and graphite and platinum the electrodes; the 
acid containing also a small proportion of potassic chlorate, as 
the second electrolyte. The potassic chlorate may be replaced 
by peroxide of chlorine. The graphite may be replaced by 
ordinary battery carbon. The carbon gradually disappears. 

It is a singular phenomenon that with continuous and 
uniform currrents, the nerves in a human body are not as 
sensitively affected as if the same current is interrupted. A 
shock is felt if the current is rapidly alternated, closed and 
opened, or undulated or vibrated in any manner. An irritation 
of the nerves of the tongue by an electric current produces a 
sensation of taste, and so also the exciting of other organs pro- 
duces their peculiar sensations. Even after death the nerves 
may be contracted. Certain cases are reported in which life 
was restored by exciting the respiratory muscles. 

Of all chemical elements, carbon is the only one which has 
not been melted by means of the electric current, but it has 
been heated to such a high temperature by the current as to weld 
two pieces together, the carbon becoming soft while hot, like 
wrought iron. With ordinary commercial electric lighting currents 
wire of any metal may be melted, and even volatilized, in which 
condition they burn by uniting with the oxygen of the air, forming 
oxides. Differently colored flames are produced according to 
the metal burned. Platinum and iron, tin and zinc give approxi- 
mately white light. A metallic sheet held in front of an alternat- 
ing or intermittent current magnet becomes hot in proportion 
to the strength of the current, while the magnet remains 
comparatively cool. The eddy or Foucault currents in- 
duced in the plate are the cause of its being heated. 
A metallic core put within a vibratory current magnet also 
becomes hot. 

Two plates of the same metal which have just served to con- 
duct a current into and out of a conducting compound liquid, 
can of themselves furnish a current through an electric con- 
ductor, connecting the two plates. 

If the two plates are lead, and the liquid, dilute sulphuric 
acid, the electricity thus stored is due to the electrolytic forma- 
tion upon the respective plates of the peroxide of lead and the 
pure reduced lead. After the passage or exit of the stored cur- 
rent, the lead has united with oxygen and become a lower oxide 
of lead, while the peroxide of lead parts with its oxygen and 



101 

becomes the lower oxide of lead also. Local actions convert 
lead into the objectionable sulphate of lead. 

The storage, so-called, of electricity by the ordinary storage 
battery is not a correct statement. The electricity in passing 
from one lead plate to another forms new chemical compounds. 
The subsequent chemical affinity during discharge causes new 
compounds to be formed with accompanying electricity. In 
brief, the electrical force is converted into chemical force, which 
remains as long as desirable. Subsequently, the chemical force 
is converted into electrical force. 

Any chemical compound of a metal attached to one electrode 
and capable of uniting with oxygen, when coupled electrically 
with a second electrode provided with a chemical compound of 
the same metal capable of uniting with hydrogen, will, in an 
electrolyte containing hydrogen and oxygen (for example, water 
containing a solution of the salt of said metal), generate an 
electric current, whether these chemicals have been produced as 
in storing electricity or by any other manner known or unknown. 
To store electricity consists, therefore, in producing chemi- 
cal changes in given compounds and using the new com- 
pounds in such a manner as to produce an electric current, or 
else it consists, as in the case of the Leyden jar, in charging a 
metallic mass with electricity while separated from a second 
metallic mass by glass or similar insulator. When the two are elec- 
trically or metallically joined, the stored electricity is obtained 
for use. 

The metals and alloys which have been electrically welded 
to themselves are: Gold, silver, silicon, phosphor and aluminium- 
bronze ; brass, bismuth, copper, zinc, platinum, malleable 
wrought and cast iron ; antimony, magnesium, lead, manganese, 
alloy of aluminium and iron ; gun metal, German silver, 
fusible metal, crescent, Bessemer, stub, chrome, musshet and cast 
steel, and tin. Example : Lead has been electrically welded 
to lead; gold to gold, &c. Different metals which have been 
welded together are: Copper to either gold, silver, Ger- 
man silver, iron and brass; brass to either soft steel, 
tin, German silver, cast iron; wrought iron to either soft 
or cast steel, tool steel, , crescent steel, cast brass, German 
silver; gold to either platinum, silver, German silver and silver 
to platinum. 

Electric welding may not only be effected by the alternating 
current, but also by continuous currents. 

When an electric conductor is heated by an electric current, 
the center of the same is the hottest, the temperature being less 
and less toward the outer surface. 



102 

If two small bars of different metals — best for the purpose 
being antimony and bismuth — be laid upon each other and 
crosswise and soldered together, an instrument is obtained by 
which a sjnall electric current may be converted into "cold; " 
/, <?., if the current is in one direction the temperature of the 
joint is lowered about 4°. When the current is reversed, the 
temperature of the joint is increased an equal amount. The 
reverse of the above principle is true. If the joint is heated 
while the ends of the bars are connected by a conductor, a 
current of one direction is generated. A current of the opposite 
direction is produced if the joint is cooled. With a very deli- 
cate galvanometer a current is found to be produced, however 
small the amount of heat added to or subtracted from the joint. 
Why the cold is produced is no better known than why heat is 
produced by the passage of currents of opposite direction 
through the joint; but if the theory of heat is right, the matter 
is explained by a consideration of the motion of the molecules. 
In the one case the motions of the molecules are accelerated, 
producing heat; in the other case they are retarded, resulting in 
cold. Another way in which the temperature of a conductor is 
affected is illustrated by the following statement: When a 
metallic bar is heated at one end and cooled at the other, the 
temperature of the bar is raised to different amounts according 
to the direction of the current. The variation is so slight that 
it can be detected only by very sensitive means. The two ends 
may be respectively heated and cooled to fixed temperatures by 
boiling water and ice. A differential arrangement will best 
show the difference. Use two parallel bars, for example, of iron. 
Connect one pair of ends by a wire in boiling water and the 
other leave separate in ice water. Pass a current through the 
bars by connecting the unjoined ends to an electric generator. 
Corresponding parts of the two bars will be found to nave very 
slightly different temperatures. The current should be strong 
enough to heat both bars. It will be noticed by this arrange- 
ment that the current passes through one bar from its cool end 
to the hot, and through the other from its hot end to the 
cold. 

With the same current, a wire in a vacuum becomes much 
hotter than if the wire is surrounded by a gas, liquid or solid. 
The surrounding material conducts the heat away rapidly, while 
in a vacuum, the heat is conducted away only slowly by the con- 
ductors leading to the wire. In both cases, of course, substantially 
equal amounts of heat are given away by radiation. A given 
current will heat a round wire more than a flat one of the same 
cross-section, because the latter has a greater radiating surface. 



103 

Heat is produced by an electric spark. The electromotive force 
for an arc lamp must be comparatively high on account of the 
high counter-electromotive force. This counter-pressure is 
similar to the counter-electromotive force produced by polariza- 
tion in an electric battery. In both instances it depends largely 
upon the nature of the electrodes. In an arc lamp with carbon 
electrodes it is 36 volts; with iron and copper, 24; with zinc, 
19; and cadmium, 10. The temperatures of the ends of the 
two electrodes are widely different, although heated by the same 
spark; that of the positive being between 2,500° and 3,500° C, 
and that of the negative, between 2,000° and 2,500°. The 
minimum resistance of the heated air and gases between the elec- 
trodes is found to be i ohm, increasing to 15 sometimes. Let 
two wires of different metals touch each other. A current in 
one direction cools the joint, while a current in the opposite 
direction heats the joint. 

Mechanical motion is directly convertible into electricity by 
friction. The electricity thus produced is exactly the same as 
if obtained by chemical action, but the pressure is always 
thousands of times greater and the total energy is very small in 
comparison to the amount of power producing the friction. 

In the science of electricity often appear the terms positive 
and negative electricity. This arises from the introduction of a 
theory that electricity consists of two fluids capable of motion. 
When both together the motion is zero. When separated so far 
as not to have sufficient power to overcome any existing resist- 
ance between them, they are at rest. During the operation of 
their joining each other a current is produced. Similarly are 
heard the terms positive and negative poles of a generator. 
One electricity comes from one and the other from the other 
pole. When separated, the two electric fluids stand still. This 
theory does not agree with all facts; but it has taken strong 
hold upon the science, and serves at least as a convenient way of 
explaining most electrical effects. 

The substances named as follows are in such an order that 
each becomes negatively electrified when rubbed with any of the 
bodies following, and positively electrified when rubbed with 
any of the bodies preceding it : Gutta-percha, sulphur, resin, 
sealing-wax, caoutchouc, metals, wood, silk, cotton, glass, rock 
crystal, ivory and flannel. Illustration: If shellac is rubbed 
with flannel, the former will attract a small pith-ball suspended 
by a silk thread, and is therefore said to be negatively charged. 
The flannel will repel the pith-ball and is said to be charged 
positively. Glass is positively electrified when rubbed with silk, 
while the silk is negatively electrified. 



104 

A birdcage containing a bird may be charged with such a 
heavy charge of static electricity as would kill the same bird 
outside of the cage ; illustrating that static electricity dis- 
tributes itself on the outer surface of objects. A hollow sphere 
having a small hole and charged shows no charge inside the 
sphere. This rule has its modifications. An object within an 
object is capable of electrification. Again, if two charges of 
positive and negative electricity are passed through a metallic 
conductor, the whole mass becomes charged. 

Let a large mass such as a piece of metal mounted upon a 
dry glass rod be charged. Electricity may be taken from it in 
small quantities, as water from a pail, by touching it with a 
small piece of metal mounted upon glass. The small piece 
will be found to be charged with electricity. If touched to 
another large discharged metallic mass, as to a gas pipe, it be- 
comes discharged, when it will take another small amount from 
the first-named mass as before. 

The rate with which a mass may be discharged depends, 
among other things, upon its shape ; if angular, its discharge 
is quicker than if continuously curved like a ball. If provided 
with numerous sharp points, the discharge occurs most 
rapidly. 

When a highly charged body has a film of oil or water upon 
its outer surface, a shower is formed in consequence of the repul- 
sion occurring among the particles of the liquid. Similarly, a 
candle flame brought near the body is repelled as if by blowing 
upon it with a current of air. A light wheel having tangential 
sharp wire points rotates when delicately pivoted and charged. 
The charges should be strong, such as are produced, for ex- 
ample, by a Holtz electrical machine, or lightning, or Leyden 

Particles of dust in the air serve to discharge a body of its 
electricity. Each particle becomes charged, floats away; other 
particles do the same, and so a circulation is maintained until 
the particles have distributed the electric charge to distant ob- 
jects and the earth. Illustration: Fill a glass jar with a fine 
powder, preferably smoke, such as may be made from burning 
a little turpentine. Charge these particles electrically, as by a 
wire connected with the electrical machine. The particles keep 
carrying off the electric charge until they are all repelled and 
rest upon the. sides of the jar, leaving the atmosphere therein 
very soon comparatively clear. 

A fine powder is transferred trom one plate to another 
analogously to electroplated metal by charging the two plates 
respectively with positive and negative static electricity. The 



105 

particles become charged with the same kind of electricity as 
the plate upon which they rest, and are therefore repelled, and 
at the same time attracted by the opposite kind of electricity of 
the other plate. 

The difference between the ordinary chemical storage bat- 
tery and a condenser, both of which are electrical accumulators, 
is that in the former the electricity is transformed temporarily 
into chemical force, while in the latter the electricity remains 
electricity, and is accumulated in the sense that a great deal 
exists on a comparatively small surface. 

The simplest form of condenser is probably that which con- 
sists of a large plate of glass having pieces of tin-foil pasted 
upon opposite sides, with a blank margin of at least an inch. 
Connect the tin-foils with the electric machine and earth 
respectively. Soon the accumulation is so great that the con- 
denser, even after a few moments, will give a longer spark than 
the machine. Any device is a condenser which consists of 
conductors separated slightly by a non-conductor. The layer 
of insulation serves as a resistance which makes it more difficult 
for the electricity to escape to the earth. It is analogous to 
storing water by carrying it from the ocean to the top of a 
mountain. Work is thus stored up, which will be given out 
again when the water is allowed to fall upon a water-wheel. 

A condenser is kept charged by supporting the same on an 
insulator. It is discharged by electrically connecting the two 
sheets of tin-foil. 

The thinner the insulating plate between the tin-foils, the 
greater the capacity, which is also greater, the larger the sur- 
faces of tin-foil and insulating plate; but with any given con- 
denser, its capacity is limited to a fixed amount, howsoever 
large the charging electrical machine. 

Let the condenser be so constructed that the glass and tin- 
foils may be taken apart while charged. The tin-foils are found 
to be substantially void of electricity, and yet when put together 
again, a shock is received by touching, simultaneously, both 
pieces of tin-foil. The action of the tin-foil results in the 
distribution and accumulation of the electricity upon a large 
surface on each side of the glass. 

Experiment shows that after discharge of a condenser a 
residue reappears after a few minutes. Let the residue be 
discharged. After a few minutes a second residue comes, and 
so on for four or five times. The residues are very slight, but 
they show that the glass has the power of absorbing some of the 
electricity. Exactly what happens to the glass as a mass, or as 
to its molecules, is not fully known. Other insulating plates 



106 

between the tin-foils or between other thin metallic plates ex- 
hibit the same property of absorption. The amount of residues 
depends upon the amount of charge, upon the nearness of con- 
tact of the elements, upon the material of which they are 
made and upon the thinness of the insulator. If the foil is 
replaced by a liquid conductor, such as dilute sulphuric acid, as 
may be done by a change in the mechanical construction of the 
condenser, the residual charge is found to exist after a few 
moments; but if the liquid is given a shock right after the first 
discharge, the residual charge may be detected within a few 
seconds instead of minutes. The device may be made of two 
concentric glass vessels of slightly different sizes placed one 
within the other, and containing sulphuric acid. 

If two pieces of gold-leaf are held together at one end, they 
spread apart when electrified. They become thereby charged 
with the same same kind of electricity and repel each other. 
Motion is therefore one of the effects of frictional electricity. 

When large amounts of static electricity are desired, the 
Leyden battery is used, which consists of several condensers 
connected in series. 

If a condenser is discharged through a conductor, as may be 
done by connecting the pieces of tin-foil with a wire, the cur- 
rent which passes is continuous, but not uniform. It is vibratory. 
It is similar to releasing a spring from tension; it has a contin- 
uous but oscillatory motion until it comes to rest. 

If a condenser is discharged through the air by using two con- 
ductors each touching a tin-foil, but not quite touching each 
other, the discharge is abrupt, and the current formed is inter- 
mittent, consisting of a rapid succession of small impulses. 

Electricity has an effect upon the human body and upon 
animals in general. Beginning with small and taking gradually 
greater and greater shocks, the elbows feel it first most strongly, 
then the chest, and finally the stomach. An army of 1,500 men 
once took a shock by joining hands. They felt it strongly. 
Those at and nearest the center get the least shock, which is 
explained that some leaks to earth before the central men re- 
ceive it. The discharge of a large battery may be retarded by 
passage through a wet rope. 

The spark which is formed by the disruptive discharge has 
different colors according to the nature of the terminals, and 
some of the material is volatilized and passes from one pole to 
the other. Thus, with gold and silver, some of the silver is 
deposited upon the gold, and some of the gold upon the silver. 
Carbon terminals give a yellow spark; ivory, a beautiful red, 
and copper, green, especially if the copper is first covered with 



107 

a coating of silver. The color varies also with the nature of 
the gas in which the sparking occurs. In a vacuum it is violet; 
in hydrogen, red; in the ordinary atmosphere, white; in a 
partial vacuum, red; in oxygen, white; and in mercury vapor, 
green. When the spark is produced, a sound occurs, whose in- 
tensity depends upon the magnitude of the cause of the spark. 
As is well known, in the case of lightning, the noise is very 
great. Even with slight sparks the noise is quite striking and 
peculiar when made in nitrogen gas. The sound in all cases is 
due to vibrations communicated to the air. When the spark 
occurs, the gas is momentarily intensely heated, causing a rare- 
faction. On suddenly cooling, condensation of the air occurs, 
and both taken together produce the sound. In addition, the 
sound is also thought to be caused by the spark making a hole 
through the air, /. ^., a vacuum; when the spark ceases, the air 
rushes into the hole, causing a condensation. This hole-forma- 
tion idea is not at all unreasonable, because a powerful spark 
will pass through glass or carboard and other insulators placed 
between two pointed terminals, and a very fine hole is formed, 
which is so small as to be invisible. Make the hole near the 
bottom of a glass tube closed at one end. Hold the closed end 
under water and blow into the tube. Very small bubbles will 
be seen passing up through the water from the hole. 

With any given spark it has the most light-giving power, 
the greater the intensity of the discharge. When the discharge 
takes place between sharp points, the spark has the appearance 
of a brush; when between ball-shaped terminals, the spark is 
linear, and often zig-zag, as in lightning, the earth and the clouds 
being the balls. 

A line of sparks may be formed by letting the discharge take 
place through successive conductors all but touching each other. 
Thus, let the pieces be in a straight, curved or zig-zag line, and 
at about .01 inch apart. Let the first and last pieces be con- 
nected to the pieces of tin-foil upon the condenser. At the 
ends of each piece a spark is visible, so that the effect is that 
of a line of light. In this manner pictures of light may be made. 

The spark is accompanied by heat, as illustrated by pro- 
ducing a spark upon a gas burner. The gas becomes lighted. 
Ether may also be lighted, and alcohol, if first warmed. 

Let the discharge be made through a very fine platinum wire. 
The wire is slightly heated. If the spark first passes through 
cardboard, the heating of the wire is less. 

Egg shells become faintly luminous in the dark by first pass- 
ing sparks through them. So do also fruits, sugar, fluor-spar, 
and heavy spar. 



108 

Gold-leaf may be turned into vapor by pressing the same 
between two glass plates and sending a charge through the gold- 
leaf. The particles of the gold condense into a violet-colored 
powder, visible through the glass. 

Magnetize and demagnetize iron rapidly, it becomes heated; 
or repeatedly hammer a metal, it becomes heated; or rub a sub- 
stance, it becomes heated. Also charge and discharge a con- 
denser rapidly, the glass becomes heated. In all, the molecules 
are certainly set into vibration. 

Independently of any heating of the air or perforation, en- 
closed air is expanded by sparks. If the terminals are balls, 
the expansion is only instantaneous; if pointed, the air only 
slowly expands. 

The oxygen and nitrogen of the air may be caused to unite 
in small quantities by repeated sparks in a vessel of moist air. 
Blue litmus paper is turned red after the sparks have been 
passed, and the density is slightly diminished. The sparks will 
ignite a mixture of oxygen and hydrogen with the formation 
of water vapor. Coal gas and oxygen are also set on fire by 
the spark. This spark of frictional or static electricity 
will also decompose substances as water, ammonic hydrate 
(ammonia), hydric sulphide, and solutions of oxides and metal- 
lic salts; but the chemical actions of galvanic electricity (from 
the dynamo or galvanic battery) are much greater than those of 
static electricity. 

The duration of an electric spark in air is .004 second; in 
water, .018 second. 

The velocity of electricity is not accurately known, but it is 
about the same as that of light. The velocity depends upon 
the nature of the conductor and also the medium around the 
conductor. With an insulated wire in water the velocity is less 
than with such a wire in air. The velocity is independent 
of the electromotive force or diameter of the wire. 

Carbon cannot be electroplated successfully upon itself or 
another substance, but an equivalent result is obtained by 
decomposition of a hydrocarbon at a high temperature, the 
carbon forming a hard coating upon the incandescent 
surface. 

The thickness of the deposit varies in any given period 
with the temperature of the receiving substance. 

In any given electric circuit of sufficient energy heat may 
be obtained by sufficiently reducing the cross-section of the 
conductor, or by breaking the circuit and maintaining an arc 
between the two parts; or if the current is alternating, pulsatory 
or intermittent, by placing a second conductor closed upon 



109 

itself (like a ring) as close as possible (without touching) to the 
circuit named. 

Amber attracts only when rubbed, but a lodestone always 
attracts. 

What is true of amber is true of all substances, which, if 
metallic, must be supported by good insulation. 

Substances attracted by the magnet are iron and steel 
greatly, and nickel, cobalt, chromium, manganese, bismuth, 
antimony and zinc very slightly. 

Steel retains its magnetism almost perfectly when removed 
from the magnet, and becomes a second magnet, while the 
remaining substances (nickel, &c.) retain a mere trace of resid- 
ual magnetism. 

The laws of magnetic attraction are the same as those of 
gravitation. The force varies inversely as the square of the 
distance. Example: At twice the distance the force is only ^ 
as great. 

A lodestone is always a magnet, but an electromagnet be- 
comes non-magnetic upon interrupting the current which flows 
in the coils of the magnet. 

If the coils surround an iron core, the total magnetism is no 
greater than without iron; but the force is directed in the same 
direction as that of the pole-pieces formed upon the core. 

The force of gravitation exists not only between the earth 
and all substances, but between and among any and all bodies, 
and is always in the form of attraction; but magnetism and 
electrical force may be made to exhibit themselves either as re- 
pulsion or attraction. 

Of two magnets, the unlike poles thereof attract — the like 
repel each other. 

Between two pieces of rubbed substances, as amber, if the 
rubbing is done with the same material, repulsion occurs. 

Pieces of different materials rubbed together, while properly 
insulated from the hands or earth, attract one another with a 
force sufficient to overcome that of gravitation. 

The amount of repelling or attracting force is greatest in a 
dry atmosphere or vacuum and increases with the force of 
rubbing and with the efficiency of the insulation employed, but 
is limited according to the nature of the material and the 
amount of surface. 

The force of magnetism may be steered in any dirction by 
motion of the whole magnet or of the pole-pieces only. 

In electric currents of low potential, such as those generated 
by a dynamo or galvanic battery, the amount of energy carried 
by a conductor is greater, the greater the cross-sectional area„ 



110 

while with frictional electricity, or that produced by rubbing, 
the larger the exterior surface of the conductor, the better the 
electricity is conducted. 

The electrical conductivity of a metal decreases with rise of 
temperature and that of carbon increases. 

Every metal has a different degree of conductivity at the 
same temperature, among the best being silver, copper, gold and 
zinc, and among the worst being platinum and German silver. 

An electric current may be set into vibration by alternately 
increasing and diminishing the resistance at one or more points; 
by similarly varying the electromotive force or pressure of the 
current; by varying the self-induction or ''inductance;" by 
varying the induction between two or more conductors; by 
varying the temperature of a conductor in the current; by 
alternating the current ; by alternately interrupting and closing 
the circuit ; by varying the electric generation of the cur- 
rent; by varying the length or cross-section of a conductor 
(which may be solid or fluid) included in the circuit; by vary- 
ing the pressure upon carbons or similar semi-conductors in 
loose contact and in the electric circuit; by alternately cutting 
in and cutting out resistances from the circuit; by varying the 
degree of perfection of contact between two or more terminals 
of an electric circuit; by the rising and falling of a liquid con- 
ductor surrounding a solid conductor partly immersed in the 
liquid, both the solid conductor and liquid conductor being in 
the electric circuit; by sliding backward and forward two elec- 
tric terminals while in contact; by alternately heating and 
cooling a conductor whether liquid or solid; by alternately de- 
positing and removing a conducting coating; by varying the 
action of light upon the conductor, provided the same is made 
of selenium, which becomes a fairly good conductor in the light 
and loses this property immediately in the dark ; or by the 
action of light or heat upon those substances which will undergo 
a chemical change when exposed to light or heat; by varying 
the distance between an electromagnet in the circuit, and 
a piece of iron, steel or nickel, or another electromagnet in the 
same or different circuit; by varying the distance between a per- 
manent magnet wound with a coil closed upon itself and a second 
piece of steel or iron or nickel; by varying the distance beween 
two parallel conductors carrying currents from the same or 
different generators; by alternately increasing and decreasing 
the length of a coil of wire; by varying the length of a spark 
between two electrodes or electric terminals; by variation of 
chemical action; by varying the amount of surface acted upon 
by a liquid or electrolyte in a galvanic battery; by varying the 



Ill 

chemical nature of the electrolyte or ekctrodes; by heating and 
cooling the liquid or electrodes; by varying the distance be- 
tween the electrodes; by agitating the liquid; by varying the 
opposing action of a second battery in the same current; by the 
action of a varying quantity or intensity of heat upon a con- 
ductor forming a part of the circuit; by the variations of tem- 
perature upon a thermopile; by the variation of pressure of an 
atmosphere upon a thermopile; and by alternately heating and 
cooling the mineral kaoline, while included in an electric circuit 
(this mineral having the property of conducting electricity 
when heated and losing its conductivity when cooled). 

A pivoted polarized armature (/. e.^ a permanent steel mag- 
net) having one pole located between the opposite poles of an 
electromagnet included in a circuit carrying an alternating elec- 
tric current, is set into vibration in unison with the alternations. 

An alternating electric current may be converted into 
mechanical motion not only as above, but a magnet in circuit 
therewith will repel a mass of metal, which should for best 
effects be in the form of a ring, or it may be an ordinary 
solenoid having its terminals electrically connected. The coil, 
for maximum power, should be of large wire. 

An alternating, intermittent or undulatory current may be 
communicated from one circuit to another circuit or coil by 
placing the two close to each other without touching. The 
secondary current is the induced current, and the primary is the 
inducing current. The amount of energy represented in the 
secondary circuit is dependent upon the length of wire ex- 
posed to the influence of the primary and upon the cross- 
sectional area of the wire of the secondary. The secondary 
will induce a tertiary current in a third wire, and so on 
indefinitely. 

By having a very long, fine primary wire, in the form of a 
coil, and a large but short secondary wound upon or within the 
first coil, the induced current will be of low pressure and great 
quantity. An opposite effect may be obtained by opposite 
conditions. 

The motion of one coil carrying a continuous or uniform 
current to or from another closed coil will induce or increase a 
current in the latter, according to the relative directions of 
winding. 

A great variety of effects in vibrations of current may be 
obtained in a closed secondary coil by vibrating before it a coil 
carrying an alternating, intermittent or undulatory current. 

Secondary, tertiary, &c., currents have exactly the same 
properties as the primary 



112 

When a circuit Is broken a spark is formed at the point of 
rupture, and its length or licht-giving power for any given cur- 
rent is increased, the longer the wire forming the circuit and 
more yet if the wire is coiled into numerous convolutions, and 
provided also the diameter is as small as practicable. With a 
large wire of short length the spark is short, but has the maxi- 
mum heating but minimum lighting power. These properties of 
forming sparks of different magnitudes as to light and heat are 
likewise true in regard to secondary, tertiary, &c., currents. 

When the electromotive force or ])ressure is sufficiently great 
a spark will occur upon bringing electric terminals toward each 
other to a distance dependent upon the electromotive force. 

A spark may be maintained between two incombustible 
terminals or electrodes by bringing them together and then 
separating them and maintaining them at a fixed distance from 
each other; or a substantially continuous sparking may be 
obtained by rapidly vibrating the electrodes to and from each 
other, the spark being formed each time they break the circuit. 

The electric spark in air is intensely violet, but if the elec- 
trodes are combustible the color is partly changed to a 
mixture of other colors; when formed beneath the surface of 
oils, it is green; in turpentine and the sulphide of carbon, it is 
white; while it is red when formed in alcohol, and in general of 
a different color for almost every liquid. 

The pressure of enclosed air is increased by the transmission 
through it of an electric spark. 

A mixture of oxygen and hydrogen, or of hydrogen and 
chlorine gases, or of air and coal gas, or of any two or more 
gases capable of ignition by a flame, is ignited with explosive 
powers by an electric spark. 

Sparks of greatest length and of maximum chemical power 
are best obtained either by electricity from the frictional elec- 
tric machine or induction coil or lightning, while sparks of the 
greatest heat and light power are best obtained from the dynamo 
or large galvanic batteries. 

Iceland spar has the peculiar property that when forcibly 
and quickly compressed of becoming charged with electricity, 
as may be shown in the dark by its exhibiting a spark when 
touched, or by its attracting pith-balls and other light particles, 
all illustrating the principle that compressure produces static 
electricity. 

Tourmaline while heating or cooling has a charge of elec- 
tricity, and so do some other substances to a less degree, 
namely : Axenite, cane sugar, potassic tartrate, Pasteur's salt, 
topaz, phrenite, scolezite, zinc silicate and boracite. 



113 

Sulphur when melted in a glass vessel becomes charged with 
electricity, as may be proved in the dark by seeing a slight 
spark between it and a pith-ball loosely in contact therewith. 
Light will produce static electricity. Thus, place fluor-spar in 
the sunlight or electric light. Heat electrifies it also. 

The first Leyden jar ever made consisted of a corked bottle 
containing water and a wire passing through the cork into the 
water. After charging, it could be discharged by holding the 
bottle in one hand and touching the wire with the other, there- 
by illustrating the principle that electricity can be stored in a 
bottle. 

Frictional electricity may be converted into magnetism by 
twisting a fine platinum wire into a coil, inserting a fine steel 
needle wound with silk thread, and passing a succession of 
electric sparks through the coil. The needle becomes a weak 
permanent magnet. 

Upon exposing a mixture of chlorine and hydrogen to the 
light of an arc lamp they combine with the formation of hydro- 
chloric acid. Also the chemical effect of the light from the 
spark is illustrated by its power to turn chloride of silver 
black. 

The spark produced by statical as well as galvanic elec- 
tricity produces chemical action, as illustrated by the fact that 
electrodes when immersed in a conducting compound liquid 
cause decomposition. In the case of galvanic electricity it is 
not necessary that the electrodes be so close to each other as to 
produce a spark. 

While it is true that upon rarefaction of enclosed air the 
luminosity thereof becomes increased, it has been lately shown 
that with a maximum obtainable vacuum the light becomes 
extinct, electrodes being supposed to extend into the enclosed 
air and charged with frictional electricity. 

The spark or arc and therefore, also, the resistance of the 
circuit may be varied by varying the material of the electrodes; 
the distance between the electrodes; the homogeneity of the 
structure; the chemical composition of the fluid in which the 
arc is formed; the motion of the fluid or the temperature of the 
electrodes. 

In any given arc lamp in a primary the positive electrode 
becomes of a higher temperature than the negative, while if 
in a secondary current the opposite is true. 

The following are the leading types of alternating electric 
current motors : (a) An ordinary direct current series motor 
will operate with an alternating current. (^) An alternating 
electric current generator acts as a motor when in circuit with 



114 

a second similar generator driven by mechanical power; but the 
motor is not self-starting, {c) A motor will operate in which 
provision is made for passing the impulses of opposite direction 
through different field magnets so as to get continuous north 
and south poles, {d) The combination of an ordinary alternate 
and direct current motor, (t^) A motor in which the magnetic 
poles of either the armature or field magnet are not stationary, 
but are progressively shifted. (/) A motor in which a closed 
coil is repelled and then opened; another closed coil is 
repelled and then opened, and so on, whereby an armature is 
rotated, (g) Gutmann's various types of motor, {/i) A motor 
in which the coils of the field magnet are closed upon them- 
selves, and in which the armature coils are in circuit with a 
primary or secondary circuit. 

It is important to remember the distinction of causes of 
repulsion and attraction. Like magnetic poles repel, but cur- 
rents of like direction attract each other. Unlike magnetic 
poles attract, but currents of unlike direction repel. Again, in 
the case usually met in static electricity, like charges repel each 
other, while unlike charges attract ; thus, two pith-balls both 
charged with either positive or negative repel each other, but when 
one is charged with positive and the other with negative electricity 
they attract each other. Upon the principle of currents being 
attracted or repelled, liquids may be set into motion by so 
arranging them to be the carrier of -one or both of the currents. 
The liquids may be caused to circulate. Of course, the liquid 
should be an electric conductor. 

If a copper disc is rotated, a magnetic needle, even at a 
comparatively great distance from the disc, is rotated. If a 
copper disc is strongly rotated between the poles of a powerful 
magnet it becomes hot. The plane of the disc should be 
parallel to the axes of the pole-pieces, v/hich should be quite 
close together. 

An alternating current is transformed into a substantially 
continuous current in a shunt to an arc formed between the 
terminals of a secondary coil, the respective terminals being a 
sharp point and a ball. The electromotive force should be 
sufficient to form a spark discharge. The arc is accompanied 
by a singing note or sound. An ordinary Ruhmkorff coil and 
platinum terminals may be employed. 

Magnetization of iron may be produced by successive dis- 
charges of a Leyden jar battery. The best form for a tem- 
porary magnet is that of glass tube filled with iron filings. 

An increase of temperature or " heat " decreases the 
magnetism — whether in iron or steel. 



115 

A line of light is seen to pass from one pole to the other 
located in a vacuum. A magnet applied to the side of the 
vacuum chamber attracts the line of light the same as if it were 
an iron wire. On reversing the current througli the magnet 
(/. ^., applying the opposite magnetic pole) the line of light is 
repelled. 

The continuous line of light between the poles may be 
intermitted or stratified by increasing the so-called vacuum. 

Electricity may be converted into light and heat by the use 
of a condenser made by placing mica between sheets of tin-foil, 
ozone being formed during the heating and formation of a 
luminous layer between the foil and mica. 

The spark between the terminals of a secondary coil of very 
low resistance (the primary being of high resistance, and both 
being of a good conductor, carries so much heat that when the 
spark is infinitesimally small, /. ^., when the terminals are in bad 
contact, the same soon become fused together, forming as strong 
a joint as by ordinary welding. 

The impulses of one direction in an electric current may be 
sifted from those of the other direction, and at the same time 
doubled, by passing the said alternating current through a 
battery or dynamo of the same electromotive force as that of 
the alternatmg generator. 

An alternating current is converted into a direct current by 
a pole-changer, acting synchronously with the alternations. 

A globule of mercury changes its length during the passage 
of an electric current. 

A varying impulse of current may be retarded by trans- 
mission over a circuit of many miles — the longer, the greater 
the retardation. 

It is against the principles of mechanics for an intermittent 
current to transmit articulate speech, but such a current can 
transmit musical sounds. 

The rapid breaking and closing of a current produce an 
intermittent current. 

The regular and rapid varying of a current from approxi- 
mately zero to maximum produces a pulsatory current. 

The current which varies in exact proportion to any force 
which is the cause of variation is an undulalory current. 

A very peculiar manner of generating a vibratory current 
consists in vibrating a wire made of different metals. Such a 
vibrating wire acts as an electric generator of minute currents. 
When the vibrations stop, the current stops. 

Reeds of different lengths produce different musical notes 
when struck; and each reed will give but one note. Therefore, 



116 

if of Iron, and vibrated in front of an electromagnet, a musical 
telephone transmitter is obtained, and will operate a receiver 
constructed in the same manner. 

Instead of acting by variation of magnetism, as above, the 
current may be intermitted by the vibrating reeds in so far as 
the transmitter is concerned. In both cases, the vibration of 
any particular reed in the receiver will result in the vibration of 
the reed of the same length in the receiver; but no other reed 
of the latter will vibrate. 

Among the semi-conductors which convert sound into elec- 
tric vibrations when employed as loose contacts in an electric 
circuit, as in the carbon telephone transmitter, are: Platinum 
black; paper, whose pores are filled with metallic particles; 
metallic sulphides; cork coverd with plumbago; cupric iodide; 
charcoal containing in its pores platinic perchloride; amorphous 
phosphorus; paper moistened with a conducting liquid; man- 
ganic oxide and plumbic hyperoxide; white silver powder; shot 
in a glass tube; carbon saturated with mercury. 

The best substance over any of the above is lamp-black 
mixed with some adhesive substance, such as syrup, and 
pressed into buttons under enormous pressure and carbonized. 

A glass tube filled v/ith a mixture of finely divided tin and 
zinc (white silver powder) and corked at the ends with carbon 
terminals, sealed with wax, and included in an electric circuit, 
is a sensitive rheostat for minute currents. When pulled or 
compressed a galvanometer or telephone receiver will indicate 
the fluctuation of current produced. 

Paper moistened with a mixture of potassic iodide with a 
small amount of starch paste, or if moistened with potassic 
ferricyanide, is sensitive to an electric current. If touched 
with electric terminals upon opposite sides of the paper, 
the same becomes colored blue at the point touched. By 
moistening the same with cupric sulphate the result is a 
blackening of the paper at the point touched. The sub- 
stances thus sensitive are those which are electrolytically 
decomposable into new compounds or elements which have 
a different color from the original. 

A dia])hragm, pressing upon parallel carbonized silk or 
linen threads, is thrown into vibration by a vibratory current. 
The parallel currents in the filaments variably attract or repel 
one another. 

Of two pieces of selenium included in an electric circuit, 
that one which is annealed is the more sensitive to light for 
the purpose of increasing its electrical conductivity by the 
action of light. 



117 

Sparking may be partially eliminated by providing an 
electric condenser or choking magnet of high self-induction 
in a shunt around the terminals at which the sparking tends 
to occur. A choking magnet is a long coil of fine wire upon an 
iron core. The magnet may have a closed secondary coil wound 
upon it. 

Variation of a beam of heat upon a thermopile does not 
produce immediate and proportional variation of current on 
account of sluggishness of heat; but variation of a beam of 
light upon selenium in an electric circuit produces immediate 
and proportional variation of current. 

A musical note, or at least a humming, is produced at the 
arc of an alternating current lamp; being produced by the 
rapid extinction and re-establishment of the current, the effect 
being similar to that of "singing flames." 

A peculiar manner in which a vibratory current may vibrate 
a diaphragm is that in which the latter has a metallic pro- 
jection resting upon a moving surface moistened with a con- 
ducting solution, as chalk, containing caustic potash mixed with 
mercuric acetate in the pores of the chalk. Or hydrogen dis- 
odic phosphate may be used. The moistened surface forms the 
remaining terminal. Variations of current produce variations 
of friction, and variations of friction produce variations of 
motion of the diaphragm. 

When the plates of an electric condenser are vibrated to 
and from each other, the electric charge thereon is varied in 
intensity. 

Let one circuit contain a generator, a carbon transmitter 
and two coils. Let another circuit contain a telephone 
receiver and two coils of the same electrical dimensions as 
the first two and placed respectively opposite them. Sounds 
at the transmitter are not heard in the receiver. Place 
a metal between two of the coils; the sound will be heard. 
The two coils in either circuit should be wound in opposite 
directions. 

The closing of a circuit induces a momentary extra 
current. The opening of a circuit induces a momentary extra 
opposition current; both being the greater, the greater the 
length of wire, and especially if the wire is coiled. 

The amount and duration of the extra currents vary with 
different metals, different molecular structure, and the form of 
cross-section. With iron the duration is greatest, and increases 
with the diameter of the wire. With carbon the duration is 
practically zero The duration is not varied by changing the 
electromotive force. 



118 

If the wire is bent back upon itself, so that the outgoing and 
return wires are as close together as possible without touching, 
the extra currents are nearly cancelled. 

With any given conductor of considerable length, that in 
any given portion of cross-section reacts upon that in the re- 
maining portion, illustrating that the current may be con- 
sidered as constructed of an infinite number of parallel elemen- 
tary currents. 

Self-induction and extra currents are reduced about 80 per 
cent, in iron, and 35 per cent, in copper, by employing thin, flat 
ribbon instead of circular wire. 

The extra currents in a steel wire are greater and of much 
greater duration than in a flat tape, where the duration is scarcely 
perceptible. 

Copper-plated iron wire has less self-induction than the iron 
wire itself. 

In two parallel iron and copper wires joined at the ends 
the extra currents in the copper wire are reduced over 60 per 
cent. 

An iron telegraph wire having a circular section with rapid 
currents, has more than three times the virtual resistance during 
its actual work than that supposed to be its true resistance". 

The self-induction of iron diminishes by heating the 
iron or by putting it under strain, or both. A moderate 
longitudinal strain decreases its self-induction capacity about 
40 per cent. Pass a constant current and heat an iron wire to 
red heat, allowing it to cool with the current on, or in place of 
heat magnetize the wire, or in place of magnetism give the wire 
mechanical vibrations; the result of either step is a strong 
internal circular magnetism, so that a wire thus treated has 
no longer its former amount of self-induction, which has fallen 
60 per cent. 

A bar of steel having north and south magnetic-poles may be 
magnetized so that there will be a weak north pole at the south 
pole and a weak south pole at the north pole. This is called 
superimposed magnetization. 

The number of alternations per second of an electric current 
so far obtained is claimed to be 30,000. 

A horizontally pivoted steel magnet or needle swings in a 
horizontal plane until it points north; and a vertically pivoted 
magnetic needle dips and points north, the earth itself being a 
magnet. 

A bar of iron becomes magnetic when pointed north, but 
not when pointed east or vertically; the magnetism being, how- 
ever, very slight. 



119 

The north pole of a magnet continually tends to attract its 
south pole. The center of the magnet neither attracts nor 
repels, being similar in this respect to the center of the 
earth. 

Some mineral compounds of iron are magnetic and some 
not. Iron pyrites is non-magnetic, while black oxide of 
iron is attracted to a magnet. In both cases the iron is 
chemically combined with a non-metal, and yet they possess 
opposite properties; again, although a magnet attracts a mag- 
netic substance or another magnet, magnetic substances will 
not attract each other. 

A compass needle points at a slightly different angle from 
year to year; and it] has very slight daily variations. It is in- 
fluenced to one or two degrees by the aurora borealis. In the 
polar regions this action is greatest, and occurs also before the 
appearance of the light. 

The needle generally points away from the true geographical 
pole to what is called the magnetic-pole. It would be found to 
point toward the geographical pole if carried on the following 
tour: Commence at Philadelphia, go north to Hudson's Bay; 
then go along the eastern coast of the White Sea and across the 
Caspian; then along the eastern shore of Arabia, through 
Australia, to the South Pole; along the eastern part of South 
America; returning to Philadelphia. 

All compass needles are acted upon by the earth's magnetism; 
but by attaching two parallel needles at opposite ends of a stick 
in such a manner that they point in exactly opposite directions, 
the action of the earth is neutralized. The action of the earth 
may be neutralized also by a large permanent magnet at such a 
distance from the needle as to exactly counteract the earth's 
magnetism. In either of the above cases the compass will be 
acted upon by other magnets and currents the same as if no 
earth's magnetism existed. Disturbances in the sun produce 
fluctuations of the needle. The greatest variation ever known 
was noticed a few hours after a large luminous mass was seen to 
pass over a sun's spot. A picture of the magnetic lines of force 
of a magnet may be made by sprinkling fine iron filings on a 
card held upon the poles of a horseshoe magnet. The lines 
are all curved except those in line with both pole centers. Each 
filing becomes a minute magnet. The curves are closest 
together at the poles, spreading as they radiate therefrom. The 
picture is made permanent by first waxing the paper and melt- 
ing the wax after the lines are formed. While forming, the 
paper should be slightly shaken to assist in neutralizing the 
friction. A compass needle at any position lies parallel to the 



120 

lines of force represented by the filings. The lines of force are 
similar to the rays of light, in that the more lines cut by a sur- 
face the greater their intensity upon that surface, while an 
important distinction is that the magnetic lines act only upon 
iron and slightly on only a few other substances. A bar of soft 
iron which has become a feeble magnet by holding it north and 
south (and dipped properly) becomes more and more non- 
magnetic the more it is pointed east and west. Its magnetism 
thus obtained may be made permanent by twisting or hammer- 
ing. Steel is permanently magnetized by peculiar movements 
upon a second magnet, either steel or electromagnetic. The 
magnetism is much stronger and more permanent if heated to 
212° F., then again magnetized, and then heated as before, and 
so on for six times. The manner of magnetizing is to move one 
pole of the magnetizing magnet back and forth over the steel 
bar to be magnetized. A better way is to move different poles 
of two strong magnets repeatedly each from the center to the 
opposite ends of the steel bar which is to be magnetized. If 
this steel bar joins the opposite poles of a third and fourth 
permanent magnet, the said bar will be much more strongly 
magnetized. The higher the temper of steel, the more difficult 
it is to be magnetized, but the more durable is its magnetism. 
This rule is true only for steel containing equal amounts of 
carbon. For pieces having variable amounts, the greatest 
magnetic permanency is obtained at different degrees of 
temper. It is a peculiar phenomenon that perfectly pure iron 
obtained by electroplating has the property of becoming 
slightly permanently magnetized, showing that this property is 
not absolutely due to the carbon in steel; especially does it not 
appear to be due to the carbon when it is remembered that cast 
iron contains more carbon than steel and yet is practically 
non-susceptible to being permanently magnetized. Incandescent 
and even red-hot iron are not attracted by a magnet; and a 
permanent steel magnet loses its magnetism at bright red and 
is not attracted by a magnet. A steel magnet which has been 
heated is weaker when cooled than before. When cooled from 
red heat, its magnetic force is substantially zero. If, at the 
same time a bar of steel is being magnetized, it is hammered or 
twisted, it will acquire a higher degree of magnetism. The 
falling of a steel magnet after magnetization weakens it. In short, 
twisting or hammermg after magnetization weakens the magnet. 
Twisting repeatedly in the same direction does not repeat the 
weakening, but subsequent twisting in an opposite direction 
diminishes the magnetic force. Magnetization of iron wires 
d'lninishcs the twisting power thereof. Pass sewing needles 



121 

through very small corks and float them on water. Bring a 
magnet near the same. The corks arrange themselves in 
geometrical figures, whose shape depends upon the number of 
corks. A slight motion of the water will often cause the corks 
to rearrange themselves in differently relative positions. Finally, 
a figure will be obtained which will be staple. 

Generally it may be said that magnets act only upon iron, 
nickel considerably, and two or three other metals very slightly; 
but there are exceptions, or rather magnets act upon nearly all 
substances, but in a different manner. A gas may be repelled 
by a magnet; thus let a candle-flame be used as it is visible gas; 
place the candle so that its flame is between the poles of a 
powerful magnet. The flame is repelled. Other illustrations in 
the case of gas are as follows: Place a small piece of iodine on 
a plate between the poles and apply heat. The colored vapor 
is seen to be deflected by the magnet as if by a breeze. The 
gas which is acted upon most powerfully is oxygen gas, but 
being colorless, the fact is difficult of exhibition. One of the 
best ways is to make soap bubbles with any given gas and place 
the bubbles near the poles. Liquids are also acted upon, Fill 
closed tubes, each with a different liquid, and suspend in a 
horizontal position by a silk thread. The tubes will assume a 
fixed position. With ether, alcohol, milk, water or blood the 
tube will stand at right angles to the axes of the pole-pieces; 
if of solutions of the compounds of iron or cobalt, the tubes 
will stand parallel to said axes. As to solids, a piece of cop- 
per suspended by a silk thread between the poles and rotated 
is stopped almost instantly by the magnetism. Other substances 
acted upon, especially if in the form of rods or bars, are bread, 
sugar, sulphur, alum, iodine, phosphorus, glass and rock crystal. 
It is thought that all substances are either repelled or attracted 
by magnets, provided the same are sufficiently powerful. 

A most remarkable phenomenon is that accompanying a 
spark formed between the poles of a powerful magnet. Let 
the terminals of the circuit of the magnet touch at a point be- 
tween the two poles. A sound like that of a pistol is produced. 
When a fine wire of tin, zinc, bismuth or iron under tension 
conducts an intermittent current, the wire produces a sound at 
each break of the circuit. 

Magnets are generally rigid and the poles at fixed distances 
from each other. If the magnet is straight, the poles are at a 
maximum distance and have the maximum power. When the 
distance is zero, the magnetism is not zero, but is at its mini- 
mum; as is illustrated by connecting the poles of a horseshoe 
magnet by a piece of soft iron. Other pieces will still be 



122 

attracted, but not with such force as when the poles are not 
connected by iron. If connected by other metal, except nickel, 
the magnetism is not appreciably diminished. If the magnet is 
flexible, torsional, compressible or extensible, and the poles are 
within the proper distance, they will move one way or another, 
the movement being due to an attractive force between the 
poles. A magnet for any given strength must be wound accord- 
ingly. If for a current having a high electromotive force, the 
coil should be made of a long, fine wire; if the current is one 
of low pressure, the wire should be of large diameter and 
comparatively short. When sugar is added to water it dissolves; 
but soon the degree of saturation is reached at which no more 
sugar will dissolve. So also with a magnet. Begin with a 
small current and increase it. The magnet becomes stronger 
and stronger, but soon becomes no stronger, although the 
current continues to increase. A magnetic force is the most 
steady for any given fluctuating current, when the convolutions 
of wire are more and more numerous from the ends toward 
the center. There are different ways in which water may be 
made to dissolve a solid above its normal degree of saturation; 
for example, the water may be heated. In the case of a mag- 
net more effective magnetism per unit of current is obtained if 
the iron core is made of insulated iron plates or wires. Again, 
the magnet will reach its point of saturation quicker with a 
solid than with a porous iron core. Below the point of satura- 
tion the magnetism varies with the current in the most economical 
proportion if the core is from three to four times the diameter. 
Since the breaking of a current causes a sound in the iron of 
a magnet (the iron being suitably suspended and resting against 
a sounding-board and the iron being alternately expanded and 
contracted), it is natural to infer that if iron is alternately ex- 
panded and contracted (e. g., by heat and cold) by any suitable 
means, it will become magnetic. Such is the case, but the 
magnetism is very slight. When a stone is lifted from the 
ground mechanical energy is stored ; because the stone in 
falling can perform the same work (as in driving a clock) as was 
required to lift it. So also is it the case with a small piece of 
iron pulled away from a magnet. It requires a force to pull it 
away. Work is done. Of two pieces of iron and steel of the 
same weight, the one is more attracted than the other by a 
given magnet. The shorter a magnet, the more quickly it is 
magnetized when the circuit is closed, and the more quickly it 
is demagnetized when the circuit is interrupted. Let a magnet 
be a long magnet. A piece of iron is attracted with greater 
force in the direction of the major than of the minor axis. A 



123 

piece of iron which has never been magnetized is more sensitive 
than one of the same weight and size which has been mag- 
netized; but its original condition may be obtained by reversing 
the current. An armature may be removed from a magnet by 
external force; but also by heating the magnet or armature or 
both. There is no difference in the natures of a permanent 
magnet and electromagnet; but there are certain characteristic 
differences. The former cannot be demagnetized and magnet- 
ized simply by respectively closing and opening an electric 
circuit, or varied in strength simply by varying the strength of 
the current. If a piece of steel is employed as the core of a 
magnet, the magnetism cannot be varied from zero to maximum, 
as can be approximately done with soft iron as a core. The 
friction of iron sliding upon iron may be varied by variation of 
a current, carried by a wire wound upon the iron. 

By varying the length of a magnet its magnetism is varied. 
If two magnets are in branch circuits, an increase of resistance 
in either branch will increase the magnetism of the magnet in 
the other branch. It is like two rivers branching away from 
each other and meeting again. Dam or partially dam up one 
branch and more water will flow through the other branch. 
Magnetism is diminished and almost extinguished by joining 
the ends of the coil by a wire of large size. The degree of 
saturation of a; piece of steel is increased by adding to it in the 
process of manufacture about 4 per cent, of the element 
tungsten. The magnetism is also more permanent. If any 
given movement of a bar of steel before a magnet magnetizes 
the steel, the reverse movements will almost demagnetize it. 

Motion between two magnets may be obtained with an 
alternating current by placing the magnets in series with each 
other. When either pole changes its polarity, the other does 
also, and consequently the force exerted by one magnet upon 
the other is constant as far as the senses are concerned; but 
analytically considered, the force is rapidly intermittent. 

When an alternating current is passed through an ordinary 
magnet, especially if having a great many windings, the current 
is greatly diminished; but not with the same results as obtained 
when passed through a rheostat or similar resistance. In the 
latter case the current is lost in the form of heat; but in the 
former only a very small portion of that which disappears is 
lost. This is why a magnet so used is called a choking magnet. 
It serves to stop a part of the current by stopping partially the 
generation. A choking magnet may be more or less deprived 
of this property by placing it inside of a ring of metal of 
considerable mass. The current is then hindered but very 



124 

slightly. It is found that it is difficult to move the magnet 
through the ring, and also that if the magnet is fixed, the 
ring will be repelled from the center of the magnet. 

If a copper disc is delicately suspended or balanced horizon- 
tally above the end of a vertical magnet, it is repelled by an 
intermittent current. Currents are induced in the disc which is 
consequently repelled. An alternating current may be substituted 
for the intermittent with similar effects. It is found that an 
induced current in a secondary conductor is a little behind 
time with respect to an inducing current. Consequently, when 
any given induced impluse is just about to cease, an inducing 
impluse is beginning. Consequently, replusion takes place. 

The disc and ring are equivalents in that the latter may be 
considered as composed of concentric rings. If the disc is 
placed between the magnet and the ring, the latter is not 
repelled, although it is strongly repelled more and more while 
the disc is being removed. If the ring is replaced by a coil in 
circuit with an incandescent lamp, the same is extinguished or 
lighted according as to whether the disc is or is not between the 
coil and the magnet. 

If the coil and lamp are balanced above the magnet, the 
primary current may fluctuate between considerable limits and 
yet the intensity of the light will remain constant. 

If two rings are placed over the alternating current magnet, 
it will be found difficult to slide one ring from the other, and 
when let go, they will attract each other until they are concen- 
tric rings. 

If the disc is pivoted at its center eccentrically to the 
magnet, it will rotate when the ring is held parallel to the disc. 
It is due to the attractive action between the disc and ring. 

The action of repulsion between the magnet and ring or 
disc is called by different names — hysteresis, magnetic friction 
and magnetic lag. Whatever the name, the principle is the 
same, being the motion due to the primary impluses of one 
direction upon the retarded induced impulses of the opposite 
direction. When two rings are used as described, they have 
induced currents both obtained from the magnet, and conse- 
quently the induced currents are both alike in the same direction, 
and consequently attraction takes place. 

A copper ball rotates if placed upon the disc which rests 
horizontally upon the end of the alternating current magnet. 

In general, an alternating current magnet acting upon a 
closed conductor produces repulsive motion, which may by 
proper mechanism or relative disposition be rotary, recipro- 
cating, &c. 



125 

A bar made of two strips of different metals bends when 
heated by atmospheric changes of temperature or by an elec- 
tric current or other source of heat. A bar of two strips of the 
same metal, and having different amounts of radiating surfaces 
and diff'erent resistances, and electrically insulated from each 
other, does not bend by changes of atmospheric temperature, 
but does bend by the heat developed during the passage of an 
electric current, whether continuous, intermittent or alternating. 

The space immediately surrounding a wire carr>-ing a con- 
tinuous and uniform current contains what may be termed 
static or, better, stored-up energ)-. A second wire parallel to 
the first will receive no current during the existence of the 
continuous uniform current, because the field of force, or the 
space containing the stored electric energy, corresponds to air 
held under pressure by an excessive weight. Take the weight 
away, and the air will expand and produce work. Similarly inter- 
rupt the uniform continuous current. This corresponds to 
removing the weight. Immediately a current is found in the 
second wire, lasting until the first current has diminished to 
zero. If the weight is partially lifted, the expanding air will 
perform work; so also will a current appear in the second wire 
during the time that a resistance is introduced into the first 
wire circuit. Similarly, as any decrease or increase of the 
weight will V3.ry momentarily the amount of work done by the 
compressed air, so will any variation of the current in the first 
wire produce a current in the second wire. Again, as long as 
the current in the first wire is constant, no current will appear 
in the second wire. In the above cases the second wire is 
supposed to be closed upon itself like a ring. If it is an open 
circuit, it will receive a static charge in the place of a current 
at each variation of the current in the first wire. The eft'ects 
of the field of force around the first wire depends upon the 
medium which surrounds it. If iron is used, the currents in 
the second wire are greater than without it; not that there is 
any force generated, but less becomes useless by dissipation. 
The iron surrounding the wire acts as a concentrator of the 
field of force. The iron should for best effects consist of 
laminae insulated from one another and lying in planes per- 
pendicular to the axis of the wire, or else should be an in- 
sulated iron wire wound helically about the wires. The 
presence and effect of the iron about the wires may be com- 
pared to substituting the good conductor copper for carbon in 
an electric circuit. The iron is the best conductor of the 
magnetic currents forming the field of force around the 
conductors. These magnetic currents are in concentric circles 



126 

around the axis of the first conductor. The reason of lamina- 
ting an iron core may now be apparent. If not laminated, a 
static charge occurs upon the iron in a longitudinal direction, 
which is discharged as a current at each variation of primary- 
current. This current in the iron circulates longitudinally 
from one part of the iron to another. This can be more easily 
appreciated by considering that the iron which surrounds the 
wires is a tube slipped over the same, and several feet thick. 
Or more forcibly by supposing the wires are rings and the iron 
is a tube whose ends are in contact. The iron would then act 
not only as a conductor of the currents in the field of force, 
but also as a secondary conductor. Practice shows this to be so, 
because such a tubular core becomes very hot on account of 
the currents which are called Foucault currents. By lamina- 
ting the core no longitudinal currents can be conducted by the 
iron to a greater distance than the thickness of each lamina. 

A converter for intermittent currents should have an open 
magnetic core; while for alternating currents the core should be 
closed upon itself, unless the alternations are unusually slow. 
It is peculiar, though not difficult to understand, that, while the 
impulses of an intermittent current are all of one direction, yet 
the induced impulses of current formed in an adjacent closed 
secondary conductor are alternating in direction. The analysis 
of the action is thus: When an impluse of the intermittent cur- 
rent begins it must increase from zero to maximum, thereby 
inducing a current having a different direction from that which 
will be produced when the said impulse stops, /. ^., decreases 
from maximum to zero; all depending upon the principle that 
increasing and decreasing currents induce currents of opposite 
direction in a secondary conductor. 

A current of electricity in a wire has often been compared 
to a current of water in a tube; but in the one case the water 
is confined within the tube while in the other the electric cur- 
rent is not only in the wire, but also in the space surrounding 
the wire. Practically, this space is comparatively slight, being 
possible of detection for only a few feet with the highest elec- 
tromotive force currents, but theoretically it extends to an 
infinite distance. 

If a wire carrying a current is wound upon glass, the mole- 
cules of the latter undergo a new motion from that due to the 
ordinary heat vibrations. The new motions are detectible by 
polarized light. 

The greater the rate of vibration, alternation, intermission, 
undulation or other oscillation of a current in a wire, the larger 
the proportion of current found upon the surface and in the 



127 

space surrounding the wire. In electric lighting systems the 
same are much more efficient if the single conductor is replaced 
by several small conductors, or by a single tape conductor, so 
as to obtain more surface per mass. 

When a continuous-current circuit is closed or broken, 
some substance in space surrounding the conductor is set into 
vibration. These vibrations stop as soon as the current is 
uniformly continuous, but the assumed unknown substance 
(thought to be the same which propagates light vibrations) 
continues to be held in an altered condition from that before 
the circuit is broken or closed respectively. 

A proof of the latter part of the statement above becomes 
apparent by holding a compass needle over the conductor. It 
is deflected until it stands at right angles to the wire. 

Electricity is generally converted into mechanical motion by 
a magnet; but this is not the only way. Take a horizontal tube, 
whose ends are bent upwards. Fill with a conducting liquid 
like salt water or dilute sulphuric acid. Drop in a globule of 
mercury. Pass a current through the liquid. The mercury 
travels from one end of the tube to the other in a direction 
dependent upon that of the current. It moves with sufficient 
force to make it travel up hill, and moves with greater and 
greater force as the current is greater and greater. A liquid 
may be raised above its natural level by the direct action of the 
current. Divide a porous jar into two compartments by a porous 
partition and introduce a decomposable liquid, conveniently, 
cupric sulphate dissolved in water. Introduce electrodes and 
pass a current from one liquid to the other. A difference in the 
heights of the liquids occurs. The converse of the above 
phenomenon is also true. If a liquid is forced through a 
diaphragm from an enclosed compartment, a current in the 
direction of the motion of the liquid is produced, and the elec- 
tromotive force increases with the pressure. Whenever a liquid 
in a vessel is stirred, a current is produced. The liquid in the 
interior of the earth is always in motion and the earth currents 
may probably be explained on this principle. Molecules are 
set into motion by the current. This is illustrated by the arc 
lamp in which particles of carbon are carried from the positive 
electrode to the negative. A piece of iron gives forth a sound 
when magnetized by a vibrating current, being due to the mechan- 
ical motions, compressions and expansions, which are communi- 
cated to the air. A vibratory motion may be communicated to 
a globule of mercury in substantially the following manner: 
Take a vessel of dilute sulphuric acid containing a very small 
proportion of chromic acid, and place therein a globule of 



128 

mercury. Immerse an iron wire until it just touches the 
mercury. The globule of mercury will vibrate and will con- 
tinue to do so indefinitely. The mercury vibrates in a very 
regular manner. By close observation, the vibrations are seen 
to consist of elongations and contractions. It is first spherical, 
and then egg-shaped, and so on. 

An English electrical paper contains the following novel 
article by Dr. Mengarini : 

" If a platinum and acidulated water voltameter is traversed 
by an alternating current, which, by means of an adjustable 
resistance, can be kept at a constant value whilst the surface of 
one of the electrodes is gradually diminished, a point is reached 
at which the current density at the movable electrode becomes 
so great that large bubbles of gas are evolved which for a 
moment insulate a portion of the electrode from the liquid. The 
metallic surface is then capable of igniting the bubbles of gas, 
producing small explosions and flashes of light in the liquid. 
With care it is possible to render the electrode incandescent 
along its whole length, so that it is covered with a sheet of 
flame from which dart flashes of bluish light with little ex- 
plosions. At the same time on the first electrode, where the 
current density has remained constant, appears a copious evolu- 
tion of gas, without comparison greater than it was at first when 
the other electrode did not exhibit this phenomenon of recombi- 
nation. This gas is found to be a mixture very rich in hydrogen. 
If it is a salt that is being decomposed, a considerable deposit of 
metal takes place on the second electrode, which is seen by 
simple inspection, without the necessity of weighing, to be very 
much greater than that which would have taken place under 
ordinary conditions. If on the electrode whose surface has been 
kept constant, the current density is so small that no trace of 
decomposition appears on it; still, as soon as the first electrode 
commences to be incandescent, the products of decomposition 
immediately appear on the second, which, in the case of solid 
ions, at once becomes covered with a metallic deposit, just as if it 
formedthe negative electrode of a voltameter traversed by a direct 
current. A similar result occurs if one of the electrodes, without 
being covered by a sheet of gas from which starts a continuous 
series of explosions, is surrounded by liquid in a state of strong 
ebullition, so that, without any luminous phenomena, the elec- 
trode gives out a feeble sound, resembling the hum of a gnat. 
In order to carry out this experiment, it is sufficient to enclose 
the electrode in a porous cell immersed in the liquid. After 
starting the current, as soon as the density reaches a suitable 
value, the liquid enters into ebullition. If a third electrode of 



129 

platinum is placed in thq voltameter containing the two elec- 
trodes when the above experiments are being made and a wire 
carried from it to one terminal of a galvanometer, the other 
terminal of which can be connected by means of a key to either 
of the two original electrodes, it is found, on suddenly breaking 
the alternating circuit, that, whilst the electrode that became 
incandescent is either not polarized at all, or only very feebly 
so, that with the larger surface shows strong polarization, the 
direction of the current being the same as that from the copper 
pole of a volta couple. On inserting other voltameters con- 
taining sulphate of copper, nitrate of silver, etc., in series with 
the first and placing therein electrodes of such an area that 
decomposition does not occur when the alternating current 
passes through them, as soon as the above phenomenon takes 
place, the current remaining constant, an active electrolytic 
decomposition commences with deposition of copper, silver, 
etc., in each of the other voltameters." 

Hurmuzescu states in the Electrical Review (London) the 
following: 

" A fine wire stretched between two supports, one of which 
is provided with a strainer or spring, for regulating the tension, 
on being traversed by a large continuous current begins to vi- 
brate The explanation of this fact seems 

to me to lie in the interchange of heat between the wire and 
the surrounding atmosphere; this constitutes really a thermic 
motor, in which the energy expended is supplied by the 
current." 



CHAPTER XIV. 
" I've Got an Idea.' 



This is the exclamation which usually heralds the embryo of 
an invention. It has been uttered so often as to become a 
familiar expression. As soon as such an announcement is made 
the inventor knows that it is only a matter of intelligence, 
knowledge, work and practice to develop the idea into a clear 
conception, and the conception into a complete invention. 
When he arrives at the stage of being able to say : ''I've got 
an idea," he has, substantially, the invention. He has obtained 
that which he has sought. He seems enthusiastic. He makes 
sketches mentally and on paper of a device which will carry out 



130 

his idea. He obtains all the knowledge he possibly can which 
will assist him in developing the invention. He realizes the im- 
portance of practice in development and of knowing how earlier 
inventors made the quickest progress in development. He feels 
that the import of the conception is so great that he cannot know 
too much of that which he feels every inventor is supposed to 
know. He is like a man who starts a new business with which he 
is not acquainted; each day shows him his ignorance of what he 
ought to have known. He realizes the importance of preliminary 
preparation. 

What great benefits and wealth have resulted from such ideas! 
How many luxuries and conveniences have grown therefrom! 
Such ideas have singly been the foundation of a fortune. "What 
physical objects of property have outweighed in value mental 
acts called an idea ? Therefore, is it not important to inves- 
tigate the causes of ideas, learn if an idea is simple or compound, 
and if compound, to discover its element by a process of 
analysis ? If this can be done, how important it will be to a 
would-be inventor ? If an idea is something which is obtainable 
by money, work, knowledge, or any other form of acquirable 
property, the inventor may be assumed to be anxious to know 
the fact. The popular mind apparently seems to look upon an 
idea as something which has been bestowed upon a person by 
some power independent of any action on his part further 
than the passive action of reception of an idea. The very ex- 
pression forming the title of this chapter contradicts such a 
notion. The inventor says: " I've got an idea," or *' Eureka," 
meaning " I've found it." To get a thing implies action. Ho find 
a thing implies action. Again, it will probably be found by 
investigation that an idea is not a myth, but it is something. 
Chemical compounds are made by putting two or more elements 
together. If ideas are compound, much light will be obtained 
and much assistance arrived at if the compound idea can be 
analyzed. The problem before us is evidently a great one; it 
is of so much importance that an attempt to solve it cannot be 
spent in vain, even if only one ray of light is caused to enlighten 
the beginning of the road leading to its solution. 

The problem is resolved into parts represented by the fol- 
lowing questions: Is an idea single or compound ? If com- 
pound, what are its elements ? How can an idea be obtained ? 
What other useful data can be obtained by investigation ? The 
answers are most probably found hidden in examples of the 
past. The astronomer can predict eclipses because he studies 
the causes of former eclipses. The geologist can give informa- 
tion of the existence of certain substances under the surface of 



131 

any given portion of the earth without seeing those substances, 
because he knows general principles and laws pertaining to the 
fixed relations of the visible to the invisible constituents of the 
earth at other portions of its surface. Similarly, it may become 
possible to learn how to get an idea as a basis of an important 
invention, if past ideas be carefully studied, and, if compound, 
analyzed. The invention of printing is taken first as a basis for 
study. 

Coster was the first to conceive the idea of replacing hand- 
writing by printing. He had often thought what a blessing it 
would be to the people at large to be able to own books, which 
at that time were very expensive because multiplication was done 
by hand. Only rich people owned them. When he became old, 
he was in the habit of strolling into the woods, and upon one 
occasion found the initials of his fiancee, which he had carved 
upon the bark of a tree when a young man. This led him to 
cut off bark and cut it into letters, which he naturally took home, 
and finding that his grandchildren liked to play with them, 
he carved many letters and used the same as means for teach- 
ing the children to read. On one occasion he brought home 
the letters wrapped up snugly in a piece of parchment. Some 
of them remained stuck to the parchment, and after removal by 
one of the children, imprints were left upon the surface and 
attracted the attention of one of the boys, who showed them to 
his grandfather. The latter was struck with the incident as a 
wonderful phenomenon, and studied into the cause in a severely 
critical and analytical manner. He found that the pressure 
upon the letters had squeezed out some of the colored sap, which 
stuck to the parchment at all points of contact of the same with 
the letters. Was this an invention ? No. He no more had an 
invention than the boy who first saw the prints. He had already 
done more than the boy. The latter saw the prints, enjoyed the 
phenomenon. Coster did more. He sought the cause. When 
he knew the cause, he learned something he never knew before. 
He learned a fact that a bark letter containing moist sap pressed 
upon a surface of parchment paper left an imprint. This was 
knowledge, not an invention. He had been for a long time try- 
ing to solve the problem of multiplication of letters and words 
upon parchment. His idea consisted in putting this and that 
together. His idea was compound. It consisted of two ele- 
mentary constituents, by whatever name the constituents may be 
called. The two constituents were two facts, namely : {a) A 
moist letter leaves an imprint upon parchment as often as it is 
pressed thereon, (d) Duplicating books by hand is a very slow 
and expensive process. He put these two facts together and 



132 

was able to say: I've got an idea. He might have continued 
to leave either fact by itself for the rest of his life without making 
an invention. He had as a very prominent part of his knowledge 
the fact that books were made by a very slow and expensive 
process, and had been seeking for that knowledge by whicb he 
could remove the difficulty. When he obtained the other fact 
or element, it is easier to comprehend the naturalness of his 
putting the two facts together than of leaving them alone and 
separated. This principle of the action of the mind is illustrated 
by other examples If a person is intensely striving to solve a 
given problem, it is natural for him to apply knowledge almost 
as soon as it becomes a part of his education. I admit that it 
is useless to try to explain the nature of the power which 
prompted him to put the two facts together; just as it is im- 
possible at present for physicists to explain the inherent nature 
of that wonderful force which at a distance of millions of miles 
holds the planets and stars in their places; or that force by which 
hydrogen and oxygen unite and form water, which differs in 
every respect from the hydrogen and oxygen when simply mixed; 
or that force which holds a pith-ball to a piece of amber which 
has been rubbed; or that force which lights up the world day 
after day for years and years. Although the nature of these 
forces cannot be understood, yet they are just as useful to man- 
kind. The inventor and engineer make as much use of them, 
probably, as if they knew their true nature. The forces are 
employed in the same manner that a carpenter employs his tools. 
He does not know necessarily how they were made or of what 
chemical elements they consist; but he makes the same use, and 
no more or less use, of the tools because of this lack of knowl- 
edge as to their inherent nature. So, also, the nature of the 
power which prompted Coster to combine the two facts is not 
known; but experience and examples indicate that this power 
exists and acts whenever a person becomes acquainted with such 
elementary facts. The duty of the future inventor is to be awake 
to problems needing solution and to push forward to the attain- 
ment of all the knowledge he can reach; and he may continually 
feel that the power to combine exists and that it will operate as 
soon as those particular facts are clearly comprehended, which are 
such as to form, when combined, an idea. 

One or all of the facts may come by accident, or by effort, 
or by a combination of circumstances. In the particular case 
under consideration the fact of the imprints by pressure came 
accidentally. The fact came by experimenting in the case of 
Humphrey Davy's conception of the safety lamp, by which he 
became titled " Sir," and received in the first few months of its 



133 

use $12,000 collected for him by the miners of the country, 
who thus expressed their gratefulness. As in the case of Coster, 
Davy longed to make an invention whereby the fearful and re- 
peated loss of life by mine explosions would be prevented. He 
was especially spurred on by a particular explosion in which one 
hundred men were killed in a single mine within one minute. 
This made him the more eager to solve the problem. In 
accordance with the principle already pretty well established 
by other successful inventors, he becomes thoroughly acquainted 
with the problem. He studies the causes of the explosion. He 
looks into the exact chemical and physical actions which take 
place. This knowledge, to be sure, was free to all; but he be- 
comes acquainted with it, not simply from curiosity or for the 
mere sake of being well read or highly educated. He sets be- 
fore himself the knowledge in an analytical and in a systematic 
manner. He at last arrives at the sum and substance of the 
whole matter by formulating his knowledge as a fact. The " fire- 
damp," /. <?., combustible gas escaping within the mine, mixes 
with the air entering the mine. When the proportion of fire- 
damp and air arrives at a certain relation the same becomes 
ignited by the miner's lamp and explodes with great power, 
burning men, clothes, mules and all else combustible. This was 
one fact which, coupled with another, should, according to the 
lessons learned from Coster, produced the " idea " whereby the 
mine could be lighted without danger of igniting the mixture. 
Having exhausted all book knowledge, he being a great student, 
he experimented with the flame of a miner's lamp and with ex- 
plosive mixtures. Systematic and logical experimenting based 
upon previous knowledge of chemical and physical principles 
developed, among others, two facts, namely: [a) When two com- 
partments are connected by an open metal tube, and filled with 
explosive mixtures, the one may be lighted and exploded; but 
the flame will not pass through the tube and set fire to the mix- 
ture in the other compartment, (i^) The flame of an oil lamp 
will not pass through a fine wire gauze. 

To know these facts, and to know the fact underlying the 
cause of the explosion in mines, did not constitute invention as 
long as no power of the mind acted to combine them. As we 
may expect, the power did act, he got the idea, and immediately 
planned a lamp which was a device for carrying out the idea. 
The device has been modified in different ways, but the idea 
still remains the same. The mind combined them as soon as 
the right constitutent facts were presented. With Coster the 
final wanting fact came by accident. With Davy the 
final wanting facts came by systematic and logical experiment. 



134 

In the following illustrations the wanting fact was obtained by 
a search of the old scientific principles and facts. Most modern 
scientific inventions have been thus made, as, for instance, the 
telephone, kinetograph, incandescent electric lamp, air-brake, 
telegraph, mechanical telephone, steam, air and gas-engines, 
artificial ice machine, bleaching, dyeing, thermostat, electric 
meter, telescope, microscope, photography, &c. 

Many ideas forming the foundation of purely kinetic mechan- 
ical inventions are compounded in a similar sense. Lee was a 
fellow or professor at a college. He loved study more than any- 
thing else. As time passed, he soon loved a maiden more than 
his studies; but upon being married, which was against the 
rules of the college, he was left without employment, so that his 
wife was obliged to take up her former employment of knitting 
stockings. After vain attempts in getting employment, and after 
often watching the process of knitting, he recognized how slowly 
the knitting was performed, and wondered if it might be possible 
to make a machine to do the work. One fact he had to start 
with was the movement of the fingers. He studied the exact 
motions given to the yarn. He became perfectly familiar with the 
stitches, so that he soon knew how to knit by hand. This 
knowledge constituted one fact; but he felt his lack of the 
knowledge of the remaining fact necessary to give him the com- 
plete idea. He did not know anything about machinery, although 
he felt the importance of such knowledge as indicated by his 
looking up books on the subject, and especially by his visiting 
machine-shops and factories and conversing with mechanics. 
At last the power of combing facts acted, because he had the 
two which were necessary. Learning that by means of machinery 
any and all motions could be produced, he conceived the idea 
of building a stocking frame in which the motion of his fingers 
would be performed by a mechanical device. As soon as this 
idea occurred to him the embryo of the knitting machine was 
created. To know how knitting was done by hand did not exer- 
cise the power of inventing. To know that by mechanics any 
combination of motions could be produced did not exercise the 
power, but as soon as he knew both the power acted apparently 
as promptly and surely as that of magnetism when a piece of 
iron is held near a magnet. The first machine was very crude; 
but its faulty operation indicated where improvements were 
needed. Soon Lee was making a large income, and would 
undoubtedly have continued to increase it except for com- 
petitors, there being no patent law at that time. He next set up 
his machinery in France, where he received a warm welcome 
from Henry the Fourth, during whose reign Lee and his family 



135 



lived in luxury from the profits of this business in manufacturing 
his stocking frame. 



CHAPTER XV. 

Failure and Success. 



If you invent that which proves to have been invented be- 
fore, do not lose courage ; but rather let it be the means of 
showing you that you are an inventor, and that the more inven- 
tions you make, the more likely you will be to obtain novelty, 
as well as usefulness. This principle is substantiated by the 
case of Gatling, the inventor of the improved gun. He first in- 
vented the propeller wheel, in the form in which it is now used, 
but in. applying for a patent found that Ericcson had forestalled 
him. The disappointment and mortification of this failure were 
severe, because he foresaw the importance of the new method 
of propulsion; but with youth and energy he overcame its de- 
pressing effect. During the next few years he made inventions, 
which became introduced into practice, and finally, invented 
and patented the gun, which now bears his name. 

This is a good principle upon which to act. If anticipated, 
give in, and concede priority, as you have nothing else you can 
do, unless you can prove priority by proper evidence. Again, 
do not spend years upon one subject, exclusively of others. 
Perhaps your problem belongs to the same class, practically, as 
those of the Philosopher's Stone; Quadrature of the Circle; The 
Fourth Dimension; The Precise Solution of Equations of the 
Fifth Degree; or Perpetual Motion. 

Over a century ago, Hartman became so discouraged, because 
he could not solve the problem of Perpetual Motion, that he 
went and hanged himself, and only lately a believer in 
the same problem committed suicide in the city of my 
residence, leaving evidence, that his reason for so doing, was his 
disappointment in life, because he could not produce perpetual 
motion. I do not intimate that any one of my readers is under- 
taking impossibilities ; but they may be wasting time in a path 
in which others, for scores of years, have failed. I mention, as 
an example, thermo-electricity,- by contact of different metals. 
Give it up ! but if you wish to work on this subject, in general, 
try the solution of conversion of heat into electricity, in some 
other line than by the contact of different metals. Clamond 



136 



spent thirty-five years on thermo-electricity with scarcely any 
improvement over his predecessors. 



CHAPTER XVI. 

Simultaneous Inventions. 



The preceding chapter illustrates that Gatling would have 
been credited, both by honor and money, through his method of 
boat propulsion, if Ericcson had never been born. The element 
of time, alone, lost him his right to a patent. The system of 
duplex, and multiplex telegraphy was invented almost simul- 
taneously, and independently, by four individuals, in different 
countries. I know of a certain inventor whose six, out of fifty 
applications, have come into interference with pending applica- 
tions in the Patent Office. A count of the number of interfer- 
ence cases in the U. S. Patent Office, would amount probably to 
several hundred per year. 

These facts establish the following principles : — 

Important inventions are often made by independent invent- 
ors, at approximately the same time. 

I do not as a rule enter into argument upon the principles I 
state, as I undertake to establish them upon facts; but this is 
such a curious principle, that I cannot refrain from theorizing, 
slightly. As soon as a large, influential, electric company intro- 
duces the alternating electric current into commerce, inventors 
naturally, and simultaneously, turn their attention to electric 
converters, alternating current meters, and motors, and to vari- 
ous other devices peculiar to an alternating current. When any 
generic invention is introduced, it is easy to see that inventors 
undertake, simultaneously, to get a patent upon the best specific 
way of carrying out the generic invention. Such inventions 
have profited enormous fortunes. 

In view of the last principle, inventors cannot be too careful 
and quick in having their inventions properly described and at- 
tested, even if they do not apply for a patent immediately. The 
drawings and description of the first mental invention should 
be signed, witnessed, and executed before a notary public, if 
possible, on the day of conception. 

A study of Camille A. Faure's wonderful, but simple, im- 
provement upon Plante's electrical storage system establishes a 
valuable principle. The latter experimented several years upon 



137 

the storage battery, his object being the determination of the 
best metals to be employed as electrodes. He did not proceed 
as an inventor. He worked more as an investigator. He tried 
silver, gold, platinum, and other metals in the same manner that 
an engineer would test samples of wire, in order to pronounce 
which is the best. Plante learned that lead was superior to all 
other metals. To form a battery, he would pass a current 
through the plates immersed in dilute sulphuric acid, continuing 
the current for several days. Then the battery would be dis- 
charged, by allowing the current to escape through a resistance. 
The operation would be repeated until a sufficient layer of active 
material was formed upon the surface of the lead plates. 
The manufacture of a large battery would occupy about three 
months, and would consume nearly as much electrical energy as 
the device would yield during its lifetime. These experiments 
were made thirty years ago. Only comparatively lately, Camille 
A. Faure, whose name is now so familiar, considered, analyti- 
cally, the question of secondary currents, for the purpose of put- 
ting the storage system on a commercial basis. He recognized 
the importance of understanding the exact chemical nature of 
the secondary battery. He considered carefully just what 
chemicals existed, when charged, and when discharged. Faure 
learned that this material consisted of a mixture of the lower 
oxides of lead, as common red lead and litharge. Consequently, 
when he found after discharge, that the substances were red lead 
and litharge, how easy it was for him to go to a paint store and 
get these materials, and apply them to the lead plates in the 
course of a few minutes, and at the same time have a thickness 
of active material, sufficient to store as much electricity as 
would, by the Plante process, occupy perhaps six months. If 
Faure had not taken the trouble to find out the exact chemical 
composition of the materials existing, at different stages, in the 
Plante battery, it is safe to say that he would not have made the 
wonderful improvement he did. The converse is also apparently 
true. He made the invention, principally, because he took the 
pains and trouble to find out, by ordinary means, the exact com- 
position and chemical reactions in the Plante battery. Before 
formulating a principle upon this single example, let another 
case be considered, in order to obtain a second fact for estab- 
lishing the principle. 

The invention considered is that of the first dynamo. Dr. 
Pacinotti, of Florence, constructed an electric motor, which 
antedated the dynamo. He studied the motor from the stand- 
point of an inventor. He analyzed the electrical changes which 
took place in the motor, in view of improving the same, and then 



138 

constructed a greatly improved form. To show how well he 
knew the scientific principles, he suggested in a publication, that 
if a certain minute change were made in his motor, and, instead 
of passing a current through the same and obtaining power, he 
believed that he could apply power, and obtain an electric cur- 
rent. Gramme acted upon this suggestion and thus was born 
the first dynamo. 

Do not trust to accident, nor to inspiration, nor to any myth- 
ical spirit or genius to make your invention for you. Do not 
expect the invention to come to you, without any exertion on 
your part. For thirty years the electric motor was known, but 
was not operated by power to obtain a current. For thirty years 
the red lead and litharge occurred on the lead plates, after dis- 
charge. Obtaining, with a view to invention, an accurate knowl- 
edge of the scientific nature of the electric motor, and of the 
early secondary battery, was the factor which suggested the re- 
spective inventions. 

The rules based upon the above principle maybe formulated 
thus : — 

As soon as any one, either by investigation, alone, or with 
the assistance of a chemist or physicist; or as soon as a scientist, 
or any individual, announces a scientific fact, or principle not 
known before; embrace the opportunity of being the first to 
apply the fact, or principle, to a useful purpose. In reading 
periodicals, or scientific papers, have this rule of invention in 
view. Look out for the results of scientific investigation, not as 
a student, who simply reads as a matter of obtaining knowledge; 
nor as a critic; nor as a pastime; but for the single, and concen- 
trated purpose of being the pioneer in the application. As soon 
as Faure made his invention, there were scores of immediate, 
and independent, inventors, who conceived the improvement of 
compressing the active material into small cells, or perforations, 
in the lead plate, for the two-fold advantage of obtaining more 
metallic surface, and of retaining the active material in its pro- 
per place; since, if applied to a flat lead surface, it is apt to fall 
off gradually but surely. 

The question is sometimes asked by the thoughtless, of what 
use is it to spend a fee to belong to an electrical society; or to 
be a subscriber to a scientific paper ? The man who wishes to 
be a successful inventor cannot afford to despise such things. 

The history of the invention of the carbon transmitter 
strengthens the above rule of invention. In 1873 Edison dis- 
covered the scientific principle that all semi-conductors have the 
property of varying the current, according to the pressure upon 
two pieces in loose contact and in an electric circuit. Four 



139 

years later, when inventing in the subjects of telephones, he re- 
called the new knowledge, and by introducing semi-conductors 
into a circuit, and talking against them, he thereby applied the 
new knowledge to a useful purpose. 



CHAPTER XVII. 

Simplicity the Result of Specific Invention. 



It is a principle that the final type is simpler in construction 
than the generic invention. 

The first telephone transmitter was more cumbersome and 
costly than the present; while the first envelope-machine was as 
confusing in appearance as the wisps of hay in a haystack. 
Many men wonder why they could not have invented the tele- 
phone. They should be reminded of two things: they either did 
not try, or else they think that the first unsuccessful telephones 
were as simple as the present one. 

Nearly every physical invention is at first of low efficiency, 
complex and intricate in construction, and tending very much 
to drive the inventor into despair. If he has evidence that he is 
on the right track, he should not stop for such difficulties, by 
abandoning the invention and finding afterwards that others 
commenced where he left off and succeeded. It is far better, as 
a last resort, to get the assistance of another inventor at the ex- 
pense of a portion of the interest in the patent, and act thereby 
in accordance with the old proverb that " two heads are better 
than one." 



CHAPTER XVIII. 
The Age of Invention. — A Cause of Invention. 



The world has had its age of national wars; its age of geo- 
graphical discovery, as at the time of Columbus when the whole 
of the Eastern Continent seemed to give up everything and try 
to claim America; its age of scientific discovery, right after the 
time of Bacon, when physical and chemical sciences grew faster 
than ever before; its age of religious war which seems now to be 



140 

passing away, and being replaced by a tone of greater toleration; 
its age of the gold-mining panic; and now its age of invention. 
Each invention is the embryo of another invention. Electric 
lighting begets hundreds of detail inventions and improvements, 
and so with other new arts and industries. 

Sometimes, and especially in the early days of the age of in- 
vention, several generations were occupied in the perfection of 
an invention. In one generation the mental invention is made. 
In the second, the crude generic invention; and in the third, 
the perfected, specific form. Thus it was with the screw pro- 
peller. The steam engine inventor. Watt, wrote to Dr. Small in 
1770, " Have you ever considered a spiral oar for that purpose ? " 
(of propelling boats). In 1834, Francis Pettit Smith constructed 
a boat propelled by a wooden screw, driven by a wound-up 
spring. Later he built a large boat and exhibited it on a canal, 
using steam power. A few years later Ericcson constructed, and 
patented, and introduced the specific form in use at present. 

From the time that Harrison began to invent and perfect 
the chronometer, for use at sea, and obtained his reward of $50- 
000 from the English Government, forty-five years elapsed. 
He should have received $100,000, as that was the reward 
offered. The good King of Sardinia, however, bought four of his 
chronometers, paying voluntarily $20,000 for them, stating that 
it was a small recompense for the time spent by him for the 
general good of mankind. As contrasted with the above almost 
ancient inventions, it is very striking to note the rapidity with 
which our present inventors complete the commercial specific 
invention and reap the fruits of their labors. 



CHAPTER XIX. 
The Government Favorable to Inventors. 



The Government not only protects an invention by a patent, 
but also by requiring duty paid upon certain articles manufac- 
tured in a foreign country. Six years ago I ordered an Ayrton 
and Perry voltmeter from England and paid $20 duty, which 
now goes as profit to the American inventor, since the American 
style has become so popular; consequently the inventor is bene- 
fited very directly. The new duty on tin is so high that capital- 
ists have incorporated companies for mining tin in the United 
States, where its ore occurs abundantly. This opens a new field 



141 

for the inventor to experiment and produce the best process for 
the particular kind of ore found in this country. No wonder 
the people, through the Government, favor the inventor. Two- 
thirds of the wealth of this country are due to invention. The 
wonderful invention of the telephone is a self-evident proof of 
the value of Government protection and encouragement to in- 
ventors. Howe made one million dollars from his invention 
relating to sewing machines. Many of my acquaintances have 
made fortunes from patented inventions. Smaller inventions 
also have a remarkable record. The rubber mat, with projec- 
tions for receiving coins, netted a handsome income to the in- 
ventor and large profits to those who promoted its interest; 
while its convenience to storekeepers was a great benefit to the 
public. 

Certain detail improvements in primary batteries, electric 
switches, telegraph relays, telephonic apparatus, electric door 
openers, insulators, dynamos, motors, electric lamps, &c., have 
handsomely rewarded the inventor through royalties, stock, or 
cash. Even such small inventions as toys are of much benefit 
to children, not only in amusing them but in the relief they 
bring to mothers and guardians; also in the instruction they 
quietly but forcibly bestow upon children. The ball and elastic, 
which cost but one-quarter of a cent to manufacture, netted a 
fortune to the patentee and manufacturer. The lead pencil, 
with rubber tip, brought $100,000 to the inventor. Copper tips 
for shoes netted millions, and such an apparently valueless 
device as the dancing jim-crow paid yearly $75,000. Large 
fortunes were also made from Pharaoh's serpents; the Wheel 
of Life; the pencil sharpener; the gimlet screw; powdered 
emery on cloth; and the rivet and eyelet for clothing. 

At the end of the next seventeen years, especially in the 
electrical industry, larger profits than ever can probably be 
named as coming to inventors from their inventions, judging 
from the speed with which so many are even now reaping the 
benefits of their brain. In view of the vast benefits directly to 
inventors and also to the people, I advise favoring all bills and 
laws for the protection of inventions and industries. To be sure 
the people are taxed. A person pays more, on the average, for a 
patented article than after the patent expires; but they can 
afford it on account of the superiority of the patented device; 
and they should pay extra for the sake of encouragement to 
inventors. It is argued that inventors invent for the love of in- 
venting; but why do they have the love. Many love their busi- 
ness; but why ? Many love to be engaged in writing novels or 
other books. Many love to be Senators and Presidents. Their 



142 

love depends upon several elements, but an important one, when 
honestly stated, is a substantial reward. Acting on this prin- 
ciple, foreign countries and societies have offered rewards to the 
inventor first solving successfully a given problem. Dr. Vander 
Weyde has stated, in a conversation on this subject, that France 
offered $100,000 to him who would make a commercially suc- 
cessful motor. That was at the time when the electric motor 
was in its infancy. Societies and corporations have made simi- 
lar offers at various times and in various countries; it is an 
admirable plan, but the inventor should consider himself fortu- 
nate that he is not dependent upon that kind of reward. The 
experience of all countries has shown that the inventor is most 
effectually encouraged by rewarding him a patent which he can 
negotiate as a piece of personal property, at his own terms, in 
his own name, and at such a time best suited to his interests, all 
according to the value of the invention which is covered by the 
patent. 



CHAPTER XX. 

Invention and Capital. 



Inventors continue to invent ! Capitalists continue to invest ! 
I am personally acquainted with an individual who, in the early 
days of the telephone, was offered one-quarter interest in the 
patent for $1,500. To another party, it is reported, the rights 
for the whole of New Jersey were offered for a mere nominal 
sum. 

Inventors and capitalists should be more willing to co- 
operate. It is too often the case that the former must pay for 
his own experiments and patent costs before a capitalist will 
even take the trouble to look into the merits of the alleged 
invention. On the other hand, it is too often true that the 
capitalist seeks to join with the inventor, but the latter wants 
too high a price at the beginning. 

Referring to the beginning of this paper, you remember I 
stated the necessity of "confidence in success." This principle 
applies equally well to capitalists. Let them join with and 
encourage the inventor. Let them take an interest, by assign- 
ment, and pay for expenses in the premises. Brains and 
knowledge are valuable and necessary and are the primary 
cause of invention, but the inventor cannot obtain protection 



143 

and try his invention practically without money. I say to in- 
ventors and capitalists join hands, not merely as a trial, but 
with a determination to succeed. Put up a few hundred dollars 
on scientific books and electrical, chemical and physical appar- 
atus for some promising inventor. If you wait until he shows 
the value of his invention, you will find the price for an interest 
is more than you care to pay. Successful inventors have almost 
universally had the assistance of capitalists; not after grant of 
patent and proof of success; not after the inventor acquired 
fame, but at the time of the embryo of the invention. 

Men of capital have more confidence at present in proposed 
inventions than in the time of Murdock, the inventor of artificial 
lighting by gas. Sir Humphrey Davy asked Murdock if he ex- 
pected to use the dome of St. Paul for the gas holder. Sir 
Walter Scott made many clever jokes about it. Wollaston 
declared that they might as well try to light London by a slice 
from the moon as to send the light through the streets in pipes. 
John Wilkenson prophesied of the proposed ship of iron, " It 
will be only a nine days' wonder, and afterwards a Columbus's 
egg." 



CHAPTER XXI. 
Accidental Inventing Exceptional. 



Every invention, before the introduction into practical use, 
passes through two stages, namely, mental and physical. 

An invention is mental when it exists as an imagination or 
conception in the mind of the inventor. 

An invention is physical when the mental invention is put 
into bodily form by hand, or by hand with the assistance of a 
convenient tool. 

A mental invention sometimes does not become a physical 
invention. The laws of nature may not permit its operative, 
physical construction. An example is that of perpetual motion. 
In the U. S. Patent Office are hundreds of applications for 
devices claimed to produce motion and force forever when once 
started. The simplest form of such an invention is a wheel 
mounted upon a shaft or axle. The same would rotate forever, 
when once started, if it were not for the retarding forces of fric- 
tion, resistance of the air, and imperfections more or less due to 
mechanical construction. I know of a case where a certain 



144 

business man, who had sufficient brains and education to obtain 
his wealth, was induced by one possessed of a mental perpetual 
motion invention to expend two thousand dollars in the con- 
struction of the physical invention. The wheel, upon which 
balls and chains and mercury were to operate, was so large that 
in one turn it would travel fifty feet. It was proposed to em- 
ploy this device principally to propel railway trains. 

A Canadian noticed that by means of a tackle a man, weigh- 
ing one hundred and fifty pounds, raised a weight of six hundred 
pounds, and after he had induced some men to construct an 
alleged automatic force-creating machine at great expense, 
they came to the sorrowful conclusion that perpetual motion 
machines were not practical, however inviting the mental 
invention. 

A mental invention sometimes does not become a physical 
invention because the inventor lacks money, technical knowl- 
edge, or diligence. Such a mental invention often becomes a 
physical invention by the assistance of a capitalist, an educated 
person, or a diligent companion. 

A mental invention fails often to become a physical inven- 
tion because it falls short of completeness. It is then more 
properly called an idea. It lacks some one or two elements to 
be supplied, perhaps, many years later either by the same in- 
ventor or by another. 

The telephone, as a physical invention, was a conveyer of 
musical and vowel sounds before it could transmit articulate 
speech, and yet the mental invention included both, and par- 
ticularly the latter. 

A mental invention of one person often fails to become a 
physical invention because of anticipation by a prior inventor. 
The later inventor either abandons the case or proceeds to 
undertake to prove priority of invention. 

Having shown that an invention may be either a mental in- 
vention or a physical invention, and that it must first be mental 
before it can be physical, it becomes necessary to state the ex- 
ception to this principle. The exception, however, very seldom 
occurs. It is sometimes remarked that the inventor stumbled 
upon the invention while experimenting upon some independent 
invention; or, that he made it purely by accident — without 
thinking. Certain chemical compounds have been made with- 
out any prior idea on the part of the inventor as to the result 
of mixing the elements to produce the compound, and also with- 
out any idea as to its usefulness and novelty. In this manner 
Bunsen discovered that freshly precipitated oxyhydrate of iron 
is an excellent antidote for arsenic poison. This accidental or 



145 

Stumbling method of inventing is very exceptional, especially in 
modern inventing. 

^:^i; Professor Brackett of Princeton College recognizes this truth 
as based upon the experience of former inventors. He says, in 
regard to Volta's invention, " It was not the mere outcome of 
happy accident, but the result of severely logical reasoning upon 
the facts which he had observed while he was investigating the 
so-called ' animal electricity' of Galvani." 



CHAPTER XXn. 

Women Inventors. 



The United States Official Gazette puplished the following: 

" The Patent Office has published, and has for sale, a vol- 
ume containing a list of women inventors to whom patents have 
been granted, from 1790 to July i, 1888." 

Investigation shows the approximate number of women 
patentees in the United States to the present date, to be 2,400, 
and that the prevailing departments of art, in which they work, 
are kitchen utensils ; articles of dress ; fabrics ; toys ; hospi- 
tal appliances ; and educational devices, especially ; but, scat- 
tered here and there we find nearly every department repre- 
sented. By far the larger portion is domestic. The total num- 
ber of men patentees in the United States in the rough is greater 
than the population of New York City. 

The woman inventor of the fluting iron made a handsome 
fortune, while those interested with her were equally profited. 
This is only one case out of many similar successes of women 
inventors. 

Some women, of course, are overworked, and some so busy 
with various matters that little time and strength are left for the 
task of inventing ; but there are thousands of intelligent, edu- 
cated, and especially wealthy women, who have more time to 
spare than men of the same standing, and these women wishing 
often for some employment, either for the sake of occupation or 
profit, waste their time waiting for something to turn up. The 
chance, in other directions, for women to gain fame or wealth 
is very limited in comparison to the opportunities for men. The 
former are confined mostly to literature, painting and music. In 
conversation with women on this subject they almost universally 
excuse themselves, or mourn their incapacity, on the ground 



146 

that they have no genius or gift for inventing. They might as 
well wait for a piano to teach them to play, without practice, as 
to wait for an invention to come to them without action. They 
should have a certain amount of conceit, and try in every way, 
and especially by practice, and systematic thought, to invent 
something which will overcome an existing difficulty. Not only 
is there a prospect of reward, but the very act of developing a 
conception begets probably the highest type of earthly 
happiness. 

One reason, as exhibited from the study of inventions, why 
women are not more prominent among inventors, is that upon 
finding a difficulty to be overcome, and abandoning conceiving 
the possibility of success, she immediately explains it to her hus- 
band, or son, who dwells upon the subject until developed into 
a complete invention, showing again the want of confidence in 
herself. Do not be surprised if the invention is not developed 
and perfected in a day. It is said that inventor Bell's father 
tried to transmit speech, and that the son followed in his foot- 
steps many years before success. It needs confidence and per- 
severance, more than luck or the indefinite quantity called 
genius. All women have the gift ; but they will never realize 
it, until they have confidence, and practice with great 
perseverance. 

I think it will be admitted that some of the greatest difficul- 
ties with the natural laws, are met with in the kitchen. The 
domestics are probably not more to blame, than those who 
ought to invent devices, which would relieve some of the heavy 
responsibilities placed upon the employed, who usually lack in- 
telligence, education, memory, &c., more than they do the moral 
virtues, such as obedience, &c. Servants formerly burned milk. 
Now they have the device where the milk is heated by boiling 
water, so that burning becomes impossible ; because it is a scien- 
tific fact that milk cannot be heated to 212° Fahrenheit in 
a vessel standing in water, and not hermetically sealed. The 
milk heater is therefore a great invention since it does not allow 
a servant to burn milk. The improved coffee pot, whereby the 
disagreeable and unwholesome elements of the coffee are re- 
moved, is likewise a remarkable invention. Some servants can 
make good bread, and others, equally competent in other things, 
cannot. This is a difficulty which I believe is not an impossi- 
bility to overcome. Some apparatus should be invented, so that 
any person, by obeying certain simple rules, can operate it, 
and produce bread of the best quality. While staying at a board- 
ing house during college life, the bad bread was successively 
due, according to the landlady, " to anew barrel of flour," "new 



147 

girl," "the dough stood too long, or too short a time," ''pota- 
toes were inadvertently omitted," " trying a new yeast cake," 
"the oven wasn't hot enough," etc. 



CHAPTER XXIII. 

Problems in Invention. 



If inventors, and those who have a love for inventing, were 
more generally acquainted with the problems known only by a 
comparatively few, progress in inventing would be much more 
rapid and superior. One man may not be able to solve a prob- 
lem, although he has worked at it for weeks; whereas another, 
having special experience in another department of industry, may 
start in a radically new direction and solve the problem success- 
fully. The mere mention of a difficulty is such an assistance 
that the one who names the problem is often (but not rightfully) 
accredited as the inventor. An attempt was made at the Patent 
Centennial at Washington, in 1891, to prove that the widow of 
General Greene was the inventor of the cotton gin. She was 
merely the one who pointed out how important a machine would 
be which would clean cotton from its seed. The story of Whit- 
ney's invention illustrates how necessary it is that the multi- 
tude should be acquainted with existing problems. Mrs. Greene, 
herself, although recognizing the difficulty, was void of the 
knowledge of mechanics, and therefore did not possess the quali- 
fication for designing any machine whatever. The story is told 
thus by the son : 

"Eli Whitney, the sole inventor of the cotton gin, was spend- 
the winter of 1793 in the family of Mrs. Greene, on her planta- 
tion, ' Mulberry Grove,' eleven miles from Savanah, Ga. On one 
occasion she had a number of officers who had served in the 
army under General Greene meet at her house to dine. They 
were Southern planters, and in the course of conversation at the 
table were lamenting the destitution of the South, saying that 
corn and indigo were the only crops — that the negroes ate up 
the corn, and that the price of indigo was so low that its culture 
did not pay, but if some machine could be devised for cleaning 
upland cotton from its seed, they could all improve their condi- 
tion and make slave-labor profitable. The hostess, Mrs. Greene, 
referred them to her young friend Whitney, who was present, 



148 

saying that he could make such a machine; that he could invent 
anything in the mechanical line — which Mr. Whitney modestly 
disclaimed. But this incident first called his attention to this 
great want, and its importance, if successful. He had recently 
graduated at Yale College, and was preparing to study law. 
However, he resolved to devote himself for a time to this inven- 
tion, and in consequence went to Savannah, searching the ware- 
houses there to find some cotton in the seed, which he had never 
seen. At length he found a small quantity, and devoted the 
rest of the winter to his invention, and produced the cotton gin, 
the same that is in general use to-day, virtually unimproved 
upon. He had invented the breast of the machine, with its 
toothed cylinder and hopper, and was thinking how he should 
dispose of the cotton when on the cylinder of saw-teeth, after 
it had been separated from the seed. Mrs. Greene, who was 
watching the progress of the invention with great interest, play- 
fully took up a hearth-brush and said : ' I can get rid of the cot- 
ton on the cylinder,' and began to brush it off, probably not 
having the remotest idea of a revolving brush, but Whitney con- 
ceived the idea of a revolving brush and applied it. But the 
brush does not constitute a cotton gin nor separate the cotton 
from its seed. Lord Macauley said : ' What Peter the Great 
had done for the advancement of Russia, the inventor of the cot- 
ton gin has equaled, and more, in promoting the power and pro- 
gress of the United States.' " 

Miscellaneous Problems. 

W. C. Barney, in the Electrical Engineer (New York), 
reminds the public that even after the expiration of Bell's patent 
for transmitting speech by the use of an undulatory current in 
a closed circuit the American Bell Telephone Co. will order 
a patent to issue upon the carbon transmitter, which now forms 
the subject-matter of two applications in interference and both 
owned by the Bell Co., which will then have protection for 
another seventeen years upon telephony broadly because the 
other form of transmitter (the magneto telephone) is not nearly 
as practical. The problem is to invent that which does not in- 
volve the principle of vibrating the current, by speaking against 
terminals, in loose contact in an electric circuit. After March 
7, 1893, the use of an undulatory current for transmitting speech 
becomes public. The editorial of the above-named paper and 
the daily press are calling loudly for accomplishing the result of 
the carbon transmitter, or microphone, by a different device. 

Under this head the inventor should be reminded of the 
fact that while the telegraph will operate between New York and 



149 

Chicago, Omaha, Denver and San Francisco, the telephone is a 
failure for distances further than Boston, and very imperfect for 
that distance. 

In the trolley system for electric railways, the trolleys now in 
use jump the wire, the car stops, and the trolley must be re- 
placed. This objection should be remedied. 

Ferry-boats are seldom known to be injured in collisions. 
Why should not the problem be solved of constructing ocean 
steamers or providing attachments whereby they are not so often 
sunk? The compartment invention is a step in this direction. 

Women are greatly annoyed by the absence of elevators for 
elevated railway stations. The problem is one for inventors, 
rather than for contractors. 

An engineering periodical wonders why there is not in the 
market a ball-bearing for steam engine shafting. The bicycle 
ball-bearing will not do for large machinery. 

The present locking nut, with steel spiral, for railways often 
fails. In fact, rusting the nut on is about as efficient. 

If a house carries on business between New York and Den- 
ver, ten days elapse before important papers can be returned. I 
for one would pay $i postage on many legal papers if they 
would go to any point in the West during about one night. 
Rapid transit for commercial and legal papers is next in import- 
ance to the telephone. 

In manufacturing illuminating gas from steam, the product 
being called water gas, the steam is passed through white-hot 
coals. It is noticed that a large portion of the incandescent 
coal at the point where the steam enters is cooled down to such 
a temperature as to become useless for decomposing the water 
into oxygen and hydrogen. 

That which is not known as physically impossible is worth 
consideration by the inventor. At the time of writing, there is a 
great drought over this section of the country, and yet within a 
mile above our heads have hung for several days enough clouds 
to form a deluge. It is difficult to support things in the thin air, 
and yet those clouds float there as if the air were mercury or 
iron. No engineer can give a reason why some water at least 
cannot be obtained from such clouds. It is the inventor's place 
to consider this problem with the help of all the knowledge he 
can possibly get. 

Some of the difficulties in storage batteries are the buckling 
of the plates, whereby they bend toward each other, and neutral- 
ize the current by touching each other; falling off of the active 
material; formation of sulphate of lead, which increases the resist- 
ance, and which is formed at the loss of an equivalent amount 



150 

of the active oxides of lead ; the great weight of a battery; the 
eating away of the terminals where they pass out of the elec- 
trolyte ; and partial polarization. 

In the form of air-brake systems using the direct pressure of 
the air, the engineer too often uses too much pressure, thereby 
wearing the wheels oval by sliding. What is the prevention or 
tell-tale ? 

At seashores, pumps driven by the waves are becoming com- 
mon, but for driving machinery a difficulty still exists, arising 
from the varying amplitude of the waves. 

The storage system is perfection, as far as the public are con- 
cerned, but death to the operating company, on account of over 
50 per cent, of the current being lost, solely by the process of 
storing. The overhead system is highly economical, but the 
public reject it for streets having handsome residences. The 
surface or underground system embodies, in theory, the best 
elements of both the former ; but — can leakage and danger be 
prevented ? 

Since hotels will insist in carrying out the law (requiring fire- 
escapes), by supplying in each room a combustible rope which 
only serves to burn and let the inexperienced circus actor drop, 
why cannot architects or others acquainted with building pro- 
vide an internal fire-escape of a fireproof nature — or provide 
that which is a part of the building and not an attachment? 
This seems easy enough, but the problem consists in getting that 
construction which will take well with the style of man who pays 
for the building. 

A telegraphic relay depends upon a spring for its delicate ad- 
justment, but the spring soon loses it elasticity. Can a relay be 
constructed so as not to be dependent upon the elasticity of a 
spring ? 

A very common accident on cable railways is that where 
people are thrown off from the platform when the engineer puts 
the final grip upon the cable. A peculiar motion occurs, which 
has thrown some of the nimblest men. 

In large buildings in New York, and other large cities, it 
occupies the letter carrier about ^ hour to distribute the 
letters in each building. Is it possible to devise advantageous 
mechanical means for doing this ? It depends upon what the 
system is when invented. 

Considerable trouble is experienced by steam boiler-makers 
because the tubes and shell separate, due to large contractions 
and expansions in cooling and heating. The cylindrical part of 
the shell has a different degree of expansion and contraction 
from that of the tubes. The problem is to provide the best 



151 

means for preventing the tubes from becoming loose in the ends 
of the boiler. 

To prolong the durability of taps for cutting internal screws, 
the difficulty is experienced, because the greater part of the 
tapping is done by the forward end of the tap, while the re- 
mainder remains practically unworn. 

In the present fire extinguisher, operated by the melting of 
solder by the heat of the fire, to let water out of a vessel upon the 
fire, the solder becomes solidified by the cold water, "thereby pre- 
venting the flow of water, at least only through the very small 
hole made at the beginning of the melting. Consequently, this 
easily fusible metal stopper seems to have its defects. 

No subject is more inviting to inventors capable of design- 
ing complicated mechanisms than that of setting up type by a 
device like a typewriter. The latest is that in which the type 
metal is melted, while the keys are for feeding the fused metal 
into a proper matrix for each letter. After use, the type are up- 
set and melted over again. This is certainly a novel idea, and 
it is being used by one or two large newspaper establishments, 
but it is not applicable to the ordinary printing-house. The 
principal cost of getting printing done is that for the setting up. 
Why should this not be capable of cheapness equal to that of 
typewriting where a copyist can operate 15,000 letters in an hour ? 

Chemists experience difficulty in keeping hydrofluoric acid, 
as it attacks glass, while platinum — very expensive — is about 
the only mgtal it does not attack. Earthenware is not suitable. 
Bottles have been made of wax, but the weakness is a defeat to 
its success. Rubber and lead are attacked, although slowly, 
making the acid impure, and experiencing leakage after stand- 
ing any considerable length of time. 

In electric welding, the larger part of the current passes, and 
is not converted into heat, as desired, at the point of welding — 
of course, the more heat there is the more current there is in the 
circuit, but still the principles of science do not teach that the 
proportion of heat to current cannot be increased. How can it 
be brought to an efficient maximum ? 

In view of more injury arising from stoves in railway acci- 
dents than from the accidents themselves, is it possible to apply 
electricity to heating the cars? It depends upon the results ob- 
tained by an analytical and synthetical consideration of this 
problem. 

It is reported by butchers that artificial hatching of chickens 
is becoming a failure. The chickens are hatched all right and 
live a few months, but are very thin and most of them die. 
There seems an important difference between the natural and 



152 

artificial. In the former the chickens are out of doors in the 
warm weather with absolutely pure air — in the latter, they are 
in a close place, with scarcely anything to breathe but carbonic 
acid gas, or other impurities, coming from the heating process. 
Does not the delicate health of the chickens arise from bad air? 
Remember that telephony was becoming a failure before the 
invention of the carbon transmitter, which produced such good 
results as to make a grand success. 

The subject of electric railways connecting cities and sup- 
plying even greater rapid transit than by steam is being agitated. 
The armature would be mounted upon the car axle, thus elimi- 
nating entirely all the numerous mechanisms of the locomotive. 
There is one difficulty, however. The present trolley is well 
enough for slow speeds; but something radically different and 
superior must be invented for making continuous electric con- 
tact between a stationary conductor and a train going at, say, 90 
miles per hour. 

There is no apparent reason why the governing of a steam 
engine should not be accomplished efficiently by electric means 
for adjusting the throttle valve. This problem has been at- 
tacked, but in such a crude manner that the ordinary mechanical 
governors have not been abandoned. 

Why do passengers on a railway train become worn out, when 
the pleasant ride through a beautiful country should be bene- 
ficial ? It is due to the smoke and coal gas from the locomotive. 
To prevent production of these nuisances is substantially im- 
possible; but how about a design of a car or a device whereby 
people may have the pure air to breathe? 

Carbon depositied by heat is well known as superior to car- 
bonized wood. The difficulty is to manufacture it in the form 
of carbon filaments for incandescent electric lamps. 

Murders take place by pistol shots in hotels, and are not 
known until the escape of the criminal. Provide protected auto- 
matic means for giving a signal at the hotel office. 

In the manufacture of carbon filaments, the same break in 
large proportion, from shrinking about 25 per cent. The problem 
is to carbonize with less breakage. 

Prof. Nichols, of Cornell, has proposed obtaining incandes- 
cence for electric lamps by providing means whereby the in- 
candescing substance is magnesia or similar infusible and incom- 
bustible substance, of a white color, instead of carbon. The in- 
candescence is reached at a much lower temperature in the 
former, and therefore also follows greater economy. 

In the manufacture of arc lamp carbons, the present diffi- 
culty is in baking them so that all the rods are at a uniform 



153 

temperature. Some are found baked perfectly and others only 
partially, so that the operation must be repeated for a large 
per cent. 

One of the most difficult problems known is to be able to 
renew carbon filaments without throwing away the bulbs. 

Who is to be the first to provide an incandescent electric 
lamp which will not " blacken " by carbon depositing on the 
inside of the bulb, or who will produce equivalent means for 
removing this objection to the lamp ? 

Wanted, a good design for electric lamp bulbs, having a 
minimum interior space, to shorten time and expense for 
exhausting, which is the most expensive step in its manu- 
facture. 

Door bell hangers do not recommend, and some refuse jobs, 
in equipping buildings with electric bells, because repair is so 
often needed. The difficulty seems to lie in the sparking; evil 
results from sparking both at the bell and at the push button. 
Otherwise the electric bell is more advantageous than the me- 
chanical. 

Incandescent lamps, to be efficient, are limited to a maximum 
of 50 candle power, and arc lamps, to a minimum of 1,000 c. p. 
The problem is to furnish a lamp equally as practical, but of a 
candle power of about 100 to 200. 

There is a continual call among housekeepers for means of 
" turning down " the incandescent lamp. Tell them that they 
may as well turn it out, as they need no match to light it with, 
and they will reply that it is not a question of economy, but of 
convenience for a night lamp, or as a means of showing as a 
signal where the lamp is in an otherwise dark room. The rheo- 
stat has been proposed, and one or two other schemes, but the 
commercially successful way still seems to be wanting. The re- 
sult to be obtained is the production of an adjustable intensity 
of light, at the limits of one candle power and the maximum. 

At high speeds, trains jump the track, and serious accidents 
occur. This generally may be looked upon by inventors as in- 
evitable; but such a decision should never be conceded by an 
inventor until he has analyzed the causes of such accidents, and 
located the fault, whether with the wheels, the construction of 
the rails, or the speed relatively to the weight; consider also 
whether prevention or cure should be aimed at. 

After the production of reading matter by the typewriter one 
must count the words. Where the matter is located irregularly 
much time is needed. A good and cheap device for counting 
the number of words made by a typewriting-machine would 
certainly have a market among typewriter copyists. 



154 

Reference is made among these problems to a substitute for 
the carbon telephone transmitter, in order to give another in- 
ventor a chance to benefit himself and others, after the 
monopoly has been so long held by another party. A similar 
case is found in time locks for safes. A time lock is of no 
value if it can be opened by any secret, before the time set. 
But suppose the clockwork stops before that time. There 
should be secret means for opening it under this condition. In 
the present system the time lock is combined in such a manner 
with a combination lock that if the clock should stop before the 
time set for opening the safe, the manufacturers can give the 
owners a combination which will open it ; but this combination 
will not open it if the clock does not stop. It seems a possibility 
that inventors could provide means whereby the owners could 
open it under the sole condition that the clockwork stops be- 
fore the proper time. It must be remembered that there must 
be no means whatever whereby the safe can be opened before 
the time set, while the clock is still working, or else the object 
of the time lock is a failure, being to prevent a thief from 
torturing the men with the secret to open the safe. 

A problem needing much attention by inventors having 
considerable mechanical knowledge is the turn-out for trolleys, 
operative when the electric car passes upon a side track. 
Although the present form only fails a few times a week, it is 
quite a wonder it does not always fail. 

The trolley support for holding the trolley upward, against 
the line, is at present made in such a variety of forms that 
this alone is evidence that there is probably no best trolley 
arm. 

It is scarcely possible to obtain a glass of sweet milk in 
restaurants if a thunder-storm is occurring within a hundred 
miles or so. The cause of acidity is well known, but the prob- 
lem of preventing it seems to be little considered. Lightning, 
/. (?., the electricity, changes oxygen into the allotropic state of 
ozone, which has a strong affinity for certain elements of the 
milk, causing an acid to form. This is a problem for chemists, 
although its solution in a simple, mechanical manner may 
perhaps be that which is conveniently applicable in the 
kitchen and restaurants by servants. 

A periodical states that one of the difficulties attending the 
use of the telephone, on long lines, is in suppressing " overhear- 
ing " from other wires, due to induction or leakage. In using 
the instrument, it is often annoying to have your conversation 
heard by those other than the one you are supposed to be 
addressing. A present method is to have a return wire instead 



155 

of using the earthy but the expense of a line is thereby nearly 
doubled. 

To provide such means that the vibrations of air produced 
by wagons, trains, horse-cars, &:c., can be changed in number 
per second to considerably below that rate which does not pro- 
duce sound to the ear, or to increase to such a rate as to 
eliminate the sensation of sound, or in other directions of 
development, let the inventor try to turn sound into silence, as 
far as the ear is concerned. The scientist can go so far as to 
tell the inventor that there is known no reason why it cannot be 
done. 

One of the difficulties in electric railway departments is that 
of repairing overhead lines, which are high in the air. 

The same cause, "retardation," which prevents rapidity of 
telegraphic transmission at long distances, is an important 
cause in preventing telephonic transmission at long distances. 

It is now apparently conceded that the last car on a train is 
the most dangerous. A friend facetiously remarked that the 
railway company ought not to have a last car. 

Heat, light, and sound may be radiated, reflected and in 
some instances transmitted through substances, and concen- 
trated into a focus. Can these properties be said to be true of 
electricity, and if so, what are their applications ? 

During the past two or three years the alternating electric 
current has become widely applied in connection with electric 
lighting. There is to-day no motor which can be operated 
commercially on a large scale by such a current. Conse- 
quently, a system of electric power cannot be combined with a 
system of alternating current lighting. Motors for alternating 
currents have been invented; but on account of their extremely 
low efficiency, are applicable only to small power, as for driving 
small ventilating fans. It has been reported that a large 
capitalist and manufacturer offered the sum of one million dol- 
lars for a patent on a successful alternating current motor for 
railways, and that electricians have agreed that a monument will 
be erected in honor of the inventor before he dies, and that in 
other ways he will be rewarded for solving one of the greatest 
difficulties in connection with electric power. The names of the 
present inventors of commercially successful alternating current 
motors, for very small power, should be mentioned in this con- 
nection. They are : Prof. Elihu Thomson, Nikola Tesla, 
Ludwig Gutmann, Lieut, F. Jarvis Patten, Chas. J. Van Depoele, 
and Prof. W. A. Anthony, with his two colleagues, Messrs. 
Jackson and Ryan. In the space of about only two or three 
years these inventors discovered valuable principles which are 



150 

perhaps merely the beginning of further developments, either by 
themselves or others. 

The best alternating motor at present is the synchronizing 
motor, combined with the improved small motor for starting. 

Since the improvement of Faure, the electro-chemical 
storage battery has been introduced on a commerical scale ; but 
if it were as economical for railways as the overhead system, 
the latter would become extinct. The storage system at present 
finds its way only where economy is not to be considered. The 
problem is one of the most difficult of the day, since the trans- 
mission of electrical energy, in storing and in recovering, in- 
volves a loss each time. Thus to. convert electrical into 
chemical energy, and then chemical into electrical, necessi- 
tates a total loss, even in the laboratory, of about twenty-five 
per cent, and in practice more yet on account of mechanical 
difficulties. One more improvement equal in magnitude to 
that of Faure over Plante would make the storage system a 
grand success. 

The wonderful invention of photography has not yet been 
superseded by that of photographing colors. The man with red 
hair has dark hair in his photograph, and for that he may be thank- 
ful; but the rosy-cheeked girl, with beautifully tinted ribbons, 
and adorned with variegated flowers, would greatly enlarge the 
sale of cameras if her picture would result in a reproduction of 
her colors. This subject was attacked in the early days of the 
art; but it may remain for electricians, especially electro- 
chemists, to combine an appropriate electrical principle with a 
chemical principle to solve the problem. Some substances 
assume different colors under the influence of light, and it is 
also true under the influence of electrolytic action. 

Perpetual motion is impossible, but the forces of nature, as 
the wind, falling water, the heat and light of the sun, the rise and 
fall of tides, the ocean's billows, the earth's magnetism, evapor- 
ation, and lighting are intermittent, and therefore, although un- 
trustworthy in their natural condition, are nevertheless forms of 
energy which cost nothing, and which are at the disposal of the 
future inventors for storage, and for sale in the shape of heat, 
light power, electricity, and chemical action. To prove that 
there is immense power in the chemical rays of the sun, it is 
only necessary to fill a vessel with a mixture of hydrogen and 
chlorine gas, close it hermetically and expose it to the sun. The 
vessel is blown to atoms, although the mixture is unaffected in 
the dark or when exposed to merely the heat of the sun. The 
actinic or chemical rays are a powerful agency on a cloudy day, 
sufficient actinic rays being present to cause the combination to 



take place gradually with the formation of a minute drop of hy- 
drochloric acid. 

Yes, there is enough power there. The power is cheap. If 
the day is cloudy, the time for storing need simply be 
lengthened. Even if every house has no yard where the device 
can be exposed to light, yet there is a roof to every dwelling 
exposed to the full daylight, and its size is proportional to 
the size of the house and therefore to the number of lamps 
therein. 

At present, the commercial form of electricity is obtained 
from fuel, such as coal ; but the heat is first changed into me- 
chanical motion, which is then changed into electrical energy. 
Electricity may be changed directly into heat or light. The 
problem is to change the force of heat directly into electrical 
energy. A steam locomotive is more ecconomical by far than 
an electric railway system ; but a heat electric engine would 
certainly be economical. 

From the beginning of the electric age until the present 
striking improvements have been made in electric generation, 
and there is no reason for expecting them to stop. 

One of the greatest difficulties with the present dynamo is 
apparent when it is realized that the only part needing atten- 
tion is the commutator, which must be kept from sparking. 
Each dynamo could be left to take care of itself if it were not 
for this difficulty. In electric railways, the commutator is in- 
jured by dust, the sparking wears it out rapidly, and the machine 
on this account alone needs attention. There is needed an elec- 
tric motor that can be locked up in a box and left there for 
weeks without attention, the current being conveyed to it by 
wires passing through the box. This is only one of the fields 
needing a commercial means of preventing sparking upon the 
rupture of reversal of a current. 

At last the electric meter appears to have met with commer- 
cial success, one form being electro-chemical and the other 
electro-mechanical. But I would not be surprised if another 
meter were invented far outweighing all others in simplicity of 
construction, accuracy of measurement, durability and con- 
venience. 

One of the greatest difficulties in the manufacture of dy- 
namos and electric motors is the apparent necessity of boring 
the pole-pieces in order that the same may be at the mininum 
inductive distance to the armature. 

A. Reckenzaun, C. E., states in a paper before the American 
Institute of Electrical Engineers: "The problem of devising 
suitable gearing for street cars carrying their own motors has 



158 

been and is still of the greatest importance. The conditions to 
be satisfied are by no means simple." 

Nikola Tesla points out that the next necessary step in the fur- 
ther development of light by great frequency of alternations of 
current, combined with very high potential, is the production of an 
insulator which will not be injured by the charge and discharge. 
He finds great difficulty because no induction coil so far made is 
able to withstand the currents of high frequency and potential 
which are obtainable. 

The last lines of the following clipping will indicate that the 
inventor's power is needed in a certain detail of marine 
machinery: 

'^Another Ship Disabled. 

" New York, July 14. — The tramp ship Endymion is re- 
ported lo have been met on July loth with her crank broken, 
struggling to reach New York. She declined the assistance of 
passing ships and is expected off Fire Island to-day. Tugs are 
in readiness to meet her when sighted. The Endymion is from 
Banon, England. She is the fourth ship which has suffered in 
this manner in a month." 

In 1 88 1, Prof. Thurston presented the following problem be- 
fore the Society of Mechanical Engineers. He says: 

'' The second of these greatest of inventors is he who will 
teach us the source of the beautiful, soft-beaming light of the 
fire-fly and the glow-worm, and will show us how to produce 
this singular illuminant, and to apply it with success practically 
and commercially. This wonderful light, free from heat and 
from consequent loss of energy, is nature's substitute for the 
crude and extravagantly wasteful lights of which we have, 
through so many years, been foolishly boasting. The dynamo- 
electrical engineer has nearly solved this problem. Let us hope 
that it may be soon fully solved, and by one of those among our 
own colleagues who are now so earnestly working in this field, 
and that we may all live to see him steal the glow-worm's light, 
and to see the approaching days of Vril predicted so long ago by 
Lord Lytton." 

In telegraphy, condensers have been used with advantage in 
preventing the bad effects of self-induction, sparking, extra 
currents, &c. It has many times been pointed out that if a 
durable condenser for large currents, such as are used in elec- 
tric light and power stations, could be invented, the efficiency of 
electric motors (especially the alternating) and dynamos could 
be greatly increased. The objection to all known condensers 
for large currents is that the insulation is easily punctured, 



159 

burned or otherwise injured by the charges they receive, render- 
ing the condenser useless. 

At the time of writing, the decision of Judge Wallace has 
upheld the Edison filament patent. How easy it would be, 
therefore, to sell to an opposing party an invention by which 
the current can, without a filament, be subdivided for producing 
lights of from lo to 20 candle power each in as economical and 
desirable a manner as by the use of the present incandescent 
electric lamp. 

Since the introduction of the incandescent electric lamp 
attempts have been made whose object is to use the great heat 
of a gas flame for producing greater intensity of light. In the 
ordinary flame only about 8 per cent, is light energy, the re- 
maining 92 per cent, being heat. 

Some effective way of preventing *' sweat spots " and '* chill 
cracks " in cast car wheels is called for. 

Recently, a telephone manager received such severe shocks 
as to be thrown down insensible, and the telephone wire was 
setting fire to the building. Others tried to get at the wire to cut 
it, but were treated likewise. They telephoned to six different 
electric light stations to turn off the lights before the remedy 
was effected. What is the best way to prevent such mishaps in 
the future, or how can any existing devices be made com- 
mercially valuable ? 

In feed cutters and similar machines great injury is often 
produced by unusual and sudden resistance coming upon the 
machine. How can the small pulley be so attached as to be- 
come loosened at a predetermined strain thereon and be subse- 
quently adjustable ? 

How long shall explosions, fires, deaths, &c., continue from 
the use of oil lamps ? Until a lamp is made which can be upset 
or tumbled around on the floor with no other injury than the 
breaking of the chimney, the inventor should feel somewhat 
responsible for damages. 

In hunting, the tremendous noise and re-echoing of the gun 
frightens the game, so that it is usually necessary to walk about 
a mile to meet more game. In other ways the noise is objection- 
able. Cannot the inventor devise means whereby silent and 
effective hunting may be carried on. It would be a great boon 
to the sportsman. 

Since the inception of photography it has doubtlessly 
occurred to many that it is probable that some inventor may 
be able to photograph, and especially to print photographs from 
negatives in the dark, by the use of substances sensitive to heat 
rays. The secret for the inventor to discover is that chemical 



160 

or combination of chemicals which will be sensitive to heat 
rays. A difficulty he will meet, not found in the case of light, 
is that heat is conducted. This difficulty, however, may not be 
insurmountable. Photographers have plenty of time to spare 
and plenty of printing to do on rainy days and in the evenings. 

George Gibbs, M. E., in a paper before the Western R. R. 
Club, proposed a problem as follows, relating to car lighting : 

"A favorite scheme for obtaining electricity at a low cost 
seems to have been to connect the dynamo to a car axle; but 
the difficulties of obtaining regular motion and current, and 
providing light when the train stops, have necessitated the em- 
ployment of accumulators as regulators and auxiliaries. In these 
plans automatic appliances are provided to cut off the current 
from the dynamo when the speed of the train falls below a 
certain rate, and to deliver the current to the batteries in the 
same direction, no matter which way the train may move. Many 
foreign railways have tried this plan, the most successful in- 
stance being of the "Pullman Limited" on the London, 
Brighton & South Coast Railway, where the system is still in 
use. The main difficulty^ and one which the International Rail- 
way Congress states has not been solved satisfactorily, is the 
method of transmission of power from the axle to the dynamo." 



CHAPTER XXIV. 

Conclusion. 



I HAVE spoken of pecuniary reward. Men have made for- 
tunes, both as inventors and as capitalists investing in inven- 
tions. Whether wealth is obtained or not, one thing will result 
from the introduction of a useful invention, as surely as heat 
results from combustion, and that is, a name which will last 
forever, as an honor both to the inventor and to his descendants. 

Napoleon's name also probably will last forever, but whereas 
he conquered nations, by producing certain blessings at great 
sacrifice of human life, benefit without sacrifice has been pro- 
duced by Archimede's screw. Barker's mill, Watt's steam engine, 
Stephenson's locomotive, Galvani's electric battery, Faraday's 
electric motor, Davy's safety lamp, Bunsen's burner, Morse's 
telegraph. Gramme's dynamo. Prof. Thomson's electric welding 
process, Plante and Faure's storage of electricity, Edison's 
incandescent electric lamp, phonogragh and carbon transmitter, 



lei 

Bell's telephone, Westinghouse's air brake, and Pullman's 
vestibule cars. 

The good which inventors do lives after them ('tis not " in- 
terred with their bones,") and their inventions are better 
memorials than monuments of gold. 

People, at large, live and think in the Present ; scholars or 
the learned are busy with the Past ; astronomers predict Future 
positions of the heavenly bodies ; but inventors apply the 
knowledge of the Past, look into the Future for new worlds to 
conquer, and supply the Present with the fruits of their labors. 



Scientific AND Mechanical 




The undersigned have a large stock of works on the Industrial 
Arts and Sciences, embracing works on 

ARCHITECTURE, 
CARPENTRY, 

BUILDING, 

ASTRONOMY, 

METEOROLOGY, 
NAVIGATION, 

BREWING, 

Distilling, Wine-Making, Chemistry, Physics, Philosophy, Coal 
Oil, Oil, Gas, Drawing, Painting, Photography, Electricity, 
Electric Telegraph, Engineering, Machinery, Mechanics, Geol- 
ogy, Mineralogy, Metallurgy, Hydraulics, Hydrostatics, Iron, 
Steel, Mathematics, Ship Building, Works of Reference, etc. 

A complete Catalogue will be sent, post paid, gratis, on 
application. 

D. VAN NOSTRAND CO., 

23 MURRAY AND 27 WARREN STS., NEW YORK. 



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